From cb909ea9e391ba66f6fd6134ddcf1ad8a604666d Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Sat, 28 Oct 2023 15:54:06 +0100
Subject: [PATCH 01/32] Allow callbacks for tuning contexts and cleanup

Also:
  * Rename `DeliveredMessages` -> `DeliveredMessagesCache`.
  * `Blackbox` no longer copies `BoundedContextBuilder`.
  * Buses are now `Closable` instead of `AutoClosable`.
  * `Closable` interface got  `closeIfOpen()` method.
  * `BoundedContext` uses `closeIfOpen()` for closing its parts.
---
 .../java/io/spine/server/BoundedContext.java  |  33 ++++--
 .../spine/server/BoundedContextBuilder.java   | 100 +++++++-----------
 .../main/java/io/spine/server/Closeable.java  |  18 ++++
 .../io/spine/server/delivery/Conveyor.java    |  16 +--
 ...sages.java => DeliveredMessagesCache.java} |   4 +-
 .../io/spine/server/delivery/Delivery.java    |   8 +-
 .../spine/server/entity/EntityLifecycle.java  |   2 +-
 .../server/integration/IntegrationBroker.java |   8 +-
 .../server/stand/InMemoryTypeRegistry.java    |  10 +-
 .../java/io/spine/server/stand/Stand.java     |   9 +-
 .../io/spine/server/stand/TypeRegistry.java   |   3 +-
 .../io/spine/server/transport/ChannelHub.java |   8 +-
 .../server/delivery/AbstractStationTest.java  |   2 +-
 .../server/delivery/CatchUpStationTest.java   |  10 +-
 .../server/delivery/CleanupStationTest.java   |   4 +-
 .../delivery/LiveDeliveryStationTest.java     |   8 +-
 .../testing/server/blackbox/BlackBox.java     |  74 ++++++++-----
 .../testing/server/blackbox/MtBlackBox.java   |   4 +-
 .../testing/server/blackbox/StBlackBox.java   |   5 +-
 19 files changed, 192 insertions(+), 134 deletions(-)
 rename server/src/main/java/io/spine/server/delivery/{DeliveredMessages.java => DeliveredMessagesCache.java} (94%)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 18a0ed9683f..6c3e4225c25 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -59,6 +59,7 @@
 
 import java.util.Optional;
 import java.util.Set;
+import java.util.function.Consumer;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
@@ -86,7 +87,7 @@
  * @see <a href="https://martinfowler.com/bliki/BoundedContext.html">
  *         Martin Fowler on Bounded Contexts</a>
  */
-@SuppressWarnings({"OverlyCoupledClass", "ClassWithTooManyMethods"})
+@SuppressWarnings("ClassWithTooManyMethods")
 public abstract class BoundedContext
         implements Comparable<BoundedContext>,
                    Closeable,
@@ -122,6 +123,8 @@ public abstract class BoundedContext
     /** Provides access to internally-used features of the context. */
     private final InternalAccess internalAccess;
 
+    private final @Nullable Consumer<BoundedContext> onBeforeClose;
+
     /**
      * Creates new instance.
      *
@@ -145,6 +148,8 @@ protected BoundedContext(BoundedContextBuilder builder) {
         this.importBus = buildImportBus(tenantIndex);
         this.aggregateRootDirectory = builder.aggregateRootDirectory();
         this.internalAccess = new InternalAccess();
+        this.onBeforeClose = builder.getOnBeforeClose();
+
     }
 
     /**
@@ -421,19 +426,29 @@ public boolean isMultitenant() {
      */
     @Override
     public void close() throws Exception {
-        commandBus.close();
-        eventBus.close();
-        broker.close();
-        stand.close();
-        importBus.close();
-        shutDownRepositories();
+        var isOpen = isOpen();
+        if (isOpen && onBeforeClose != null) {
+            onBeforeClose.accept(this);
+        }
+
+        commandBus.closeIfOpen();
+        eventBus.closeIfOpen();
+        broker.closeIfOpen();
+        stand.closeIfOpen();
+        importBus.closeIfOpen();
 
-        logger().atDebug().log(() -> format("%s", closed(nameForLogging())));
+        if (isOpen) {
+            shutDownRepositories();
+        }
+
+        if (isOpen) {
+            logger().atDebug().log(() -> format("%s", closed(nameForLogging())));
+        }
     }
 
     @Override
     public boolean isOpen() {
-        return !guard.isClosed();
+        return commandBus.isOpen();
     }
 
     final String nameForLogging() {
diff --git a/server/src/main/java/io/spine/server/BoundedContextBuilder.java b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
index 3e2f09785d0..d3c03d4cd2d 100644
--- a/server/src/main/java/io/spine/server/BoundedContextBuilder.java
+++ b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
@@ -73,8 +73,7 @@
 /**
  * A builder for producing {@code BoundedContext} instances.
  */
-@SuppressWarnings({"ClassWithTooManyMethods", "OverlyCoupledClass"})
-// OK for this central piece.
+@SuppressWarnings("ClassWithTooManyMethods") // OK for this central piece.
 public final class BoundedContextBuilder implements WithLogging {
 
     private final ContextSpec spec;
@@ -82,8 +81,8 @@ public final class BoundedContextBuilder implements WithLogging {
     private final CommandBus.Builder commandBus = CommandBus.newBuilder();
 
     /**
-     * Command dispatchers to be registered with the context {@link CommandBus} after the Bounded
-     * Context creation.
+     * Command dispatchers to be registered with the context {@link CommandBus}
+     * after the Bounded Context creation.
      */
     private final Collection<CommandDispatcher> commandDispatchers = new ArrayList<>();
 
@@ -105,6 +104,10 @@ public final class BoundedContextBuilder implements WithLogging {
     /** Repositories to be registered with the Bounded Context being built after its creation. */
     private final Collection<Repository<?, ?>> repositories = new ArrayList<>();
 
+    private @Nullable Consumer<BoundedContextBuilder> onBeforeBuild = null;
+    private @Nullable Consumer<BoundedContext> onBuild = null;
+    private @Nullable Consumer<BoundedContext> onBeforeClose = null;
+
     /**
      * Creates a new builder with the given spec.
      *
@@ -222,14 +225,6 @@ public BoundedContextBuilder enrichEventsUsing(EventEnricher enricher) {
         return this;
     }
 
-    /**
-     * Obtains {@code EventEnricher} assigned to the context to be built, or
-     * empty {@code Optional} if no enricher was assigned prior to this call.
-     */
-    public Optional<EventEnricher> eventEnricher() {
-        return eventBus.enricher();
-    }
-
     @CanIgnoreReturnValue
     public BoundedContextBuilder setTenantIndex(TenantIndex tenantIndex) {
         if (isMultitenant()) {
@@ -278,7 +273,7 @@ BoundedContextBuilder ifRepository(D dispatcher,
      * Adds the given assignee to the Bounded Context.
      *
      * @param assignee
-     *          the assignee to add
+     *         the assignee to add
      */
     @CanIgnoreReturnValue
     public BoundedContextBuilder addAssignee(AbstractAssignee assignee) {
@@ -289,7 +284,8 @@ public BoundedContextBuilder addAssignee(AbstractAssignee assignee) {
      * Adds the passed command dispatcher to the dispatcher registration list which will be
      * processed after the Bounded Context is created.
      *
-     * @apiNote This method is also capable of registering {@linkplain Repository repositories}
+     * @apiNote This method is also capable of registering
+     *         {@linkplain Repository repositories}
      *         that implement {@code CommandDispatcher}, but the {@link #add(Repository)} method
      *         should be preferred for this purpose.
      */
@@ -326,7 +322,8 @@ public BoundedContextBuilder addCommandListener(Listener<CommandEnvelope> listen
      * Adds the passed event dispatcher to the dispatcher registration list which will be processed
      * after the Bounded Context is created.
      *
-     * @apiNote This method is also capable of registering {@linkplain Repository repositories}
+     * @apiNote This method is also capable of registering
+     *         {@linkplain Repository repositories}
      *         that implement {@code EventDispatcher}, but the {@link #add(Repository)} method
      *         should be preferred for this purpose.
      */
@@ -459,8 +456,8 @@ boolean hasEventDispatcher(EventDispatcher eventDispatcher) {
         checkNotNull(entityClass);
         var result =
                 repositories.stream()
-                            .anyMatch(repository -> repository.entityClass()
-                                                              .equals(entityClass));
+                        .anyMatch(repository -> repository.entityClass()
+                                                          .equals(entityClass));
         return result;
     }
 
@@ -485,26 +482,6 @@ boolean hasRepository(Repository<?, ?> repository) {
         return ImmutableList.copyOf(repositories);
     }
 
-    /**
-     * Obtains the list of command dispatchers added to the builder by the time of the call.
-     *
-     * <p>Adding dispatchers to the builder after this method returns will not update the
-     * returned list.
-     */
-    public ImmutableList<CommandDispatcher> commandDispatchers() {
-        return ImmutableList.copyOf(commandDispatchers);
-    }
-
-    /**
-     * Obtains the list of event dispatchers added to the builder by the time of the call.
-     *
-     * <p>Adding dispatchers to the builder after this method returns will not update the
-     * returned list.
-     */
-    public ImmutableList<EventDispatcher> eventDispatchers() {
-        return ImmutableList.copyOf(eventDispatchers);
-    }
-
     /**
      * Obtains the {@link AggregateRootDirectory} to be used in the built context.
      *
@@ -564,15 +541,22 @@ public SystemSettings systemSettings() {
      * @return new {@code BoundedContext}
      */
     public BoundedContext build() {
+        if (onBeforeBuild != null) {
+            onBeforeBuild.accept(this);
+        }
         var system = buildSystem();
         var result = buildDomain(system);
-        logger().atDebug().log(() -> format("%s created.", result.nameForLogging()));
+        logger().atDebug()
+                .log(() -> format("%s created.", result.nameForLogging()));
 
         registerRepositories(result);
         registerDispatchers(result);
         ServerEnvironment.instance()
                          .delivery()
                          .registerDispatchersIn(result);
+        if (onBuild != null) {
+            onBuild.accept(result);
+        }
         return result;
     }
 
@@ -583,6 +567,22 @@ EventBus buildEventBus(BoundedContext context) {
         return eventBus.build();
     }
 
+    public void setOnBeforeBuild(Consumer<BoundedContextBuilder> consumer) {
+        this.onBeforeBuild = checkNotNull(consumer);
+    }
+
+    public void setOnBuild(Consumer<BoundedContext> consumer) {
+        this.onBuild = checkNotNull(consumer);
+    }
+
+    public void setOnBeforeClose(Consumer<BoundedContext> consumer) {
+        this.onBeforeClose = checkNotNull(consumer);
+    }
+
+    @Nullable Consumer<BoundedContext> getOnBeforeClose() {
+        return onBeforeClose;
+    }
+
     CommandBus buildCommandBus() {
         return commandBus.build();
     }
@@ -590,7 +590,8 @@ CommandBus buildCommandBus() {
     private void registerRepositories(BoundedContext result) {
         for (var repository : repositories) {
             result.register(repository);
-            logger().atDebug().log(() -> format("`%s` registered.", repository));
+            logger().atDebug()
+                    .log(() -> format("`%s` registered.", repository));
         }
     }
 
@@ -661,25 +662,4 @@ private Stand createStand(@Nullable Stand systemStand) {
         }
         return result.build();
     }
-
-    /**
-     * Creates a copy of this context builder for the purpose of testing.
-     */
-    @Internal
-    @VisibleForTesting
-    public BoundedContextBuilder testingCopy() {
-        var copy = new BoundedContextBuilder(this.spec, this.systemSettings);
-        var enricher = eventEnricher()
-                .orElseGet(() -> EventEnricher.newBuilder().build());
-        copy.enrichEventsUsing(enricher);
-        tenantIndex().ifPresent(copy::setTenantIndex);
-        repositories().forEach(copy::add);
-        commandDispatchers().forEach(copy::addCommandDispatcher);
-        commandBus.filters().forEach(copy::addCommandFilter);
-        commandBus.listeners().forEach(copy::addCommandListener);
-        eventDispatchers().forEach(copy::addEventDispatcher);
-        eventBus.filters().forEach(copy::addEventFilter);
-        eventBus.listeners().forEach(copy::addEventListener);
-        return copy;
-    }
 }
diff --git a/server/src/main/java/io/spine/server/Closeable.java b/server/src/main/java/io/spine/server/Closeable.java
index 9e24860fff3..f47c8e868ac 100644
--- a/server/src/main/java/io/spine/server/Closeable.java
+++ b/server/src/main/java/io/spine/server/Closeable.java
@@ -27,6 +27,7 @@
 package io.spine.server;
 
 import static com.google.common.base.Preconditions.checkState;
+import static io.spine.util.Exceptions.illegalStateWithCauseOf;
 
 /**
  * Base interface for server-side objects that may hold resources that need to be released
@@ -56,4 +57,21 @@ public interface Closeable extends AutoCloseable {
     default void checkOpen() throws IllegalStateException {
         checkState(isOpen(), "`%s` is already closed.", this);
     }
+
+    /**
+     * Performs the release of the resources held by this object only if it is still open.
+     * Otherwise, does nothing.
+     *
+     * @throws IllegalStateException
+     *          if an exception occurs on {@link #close()}
+     */
+    default void closeIfOpen() {
+        if (isOpen()) {
+            try {
+                close();
+            } catch (Exception e) {
+                throw illegalStateWithCauseOf(e);
+            }
+        }
+    }
 }
diff --git a/server/src/main/java/io/spine/server/delivery/Conveyor.java b/server/src/main/java/io/spine/server/delivery/Conveyor.java
index ab88e8a43a8..918e10468db 100644
--- a/server/src/main/java/io/spine/server/delivery/Conveyor.java
+++ b/server/src/main/java/io/spine/server/delivery/Conveyor.java
@@ -54,13 +54,13 @@
  * <p>Collects the state updates of the messages and allows to flush the pending changes to the
  * respective {@link InboxStorage} in a bulk.
  *
- * <p>By accessing the {@linkplain DeliveredMessages cache}, knows which messages were marked
+ * <p>By accessing the {@linkplain DeliveredMessagesCache cache}, knows which messages were marked
  * delivered by the instances of {@code Conveyor} in the previous {@code DeliveryStage}s.
  */
 final class Conveyor implements Iterable<InboxMessage> {
 
     private final Map<InboxMessageId, InboxMessage> messages = new LinkedHashMap<>();
-    private final DeliveredMessages deliveredMessages;
+    private final DeliveredMessagesCache deliveredMessagesCache;
     private final Set<InboxMessageId> dirtyMessages = new HashSet<>();
     private final Set<InboxMessage> removals = new HashSet<>();
     private final Set<InboxMessage> duplicates = new HashSet<>();
@@ -71,11 +71,11 @@ final class Conveyor implements Iterable<InboxMessage> {
      *
      * @param messages
      *         messages to process
-     * @param deliveredMessages
+     * @param deliveredMessagesCache
      *         cache of the previously delivered messages
      */
-    Conveyor(Collection<InboxMessage> messages, DeliveredMessages deliveredMessages) {
-        this.deliveredMessages = deliveredMessages;
+    Conveyor(Collection<InboxMessage> messages, DeliveredMessagesCache deliveredMessagesCache) {
+        this.deliveredMessagesCache = deliveredMessagesCache;
         for (var message : messages) {
             this.messages.put(message.getId(), message);
         }
@@ -97,7 +97,7 @@ public Iterator<InboxMessage> iterator() {
      */
     void markDelivered(InboxMessage message) {
         changeStatus(message, DELIVERED);
-        deliveredMessages.recordDelivered(message);
+        deliveredMessagesCache.recordDelivered(message);
     }
 
     /**
@@ -191,13 +191,13 @@ private InboxMessage.Builder mutableMessage(InboxMessageId id) {
      *
      * <p>This includes both the IDs of messages delivered within the lifetime of this conveyor
      * instance and of the messages delivered
-     * {@linkplain Conveyor#Conveyor(Collection, DeliveredMessages) before it}.
+     * {@linkplain Conveyor#Conveyor(Collection, DeliveredMessagesCache) before it}.
      */
     Set<DispatchingId> allDelivered() {
         var recentlyDelivered = recentlyDelivered()
                 .map(DispatchingId::new)
                 .collect(Collectors.toSet());
-        var result = Sets.union(recentlyDelivered, deliveredMessages.allDelivered());
+        var result = Sets.union(recentlyDelivered, deliveredMessagesCache.allDelivered());
         return result;
     }
 
diff --git a/server/src/main/java/io/spine/server/delivery/DeliveredMessages.java b/server/src/main/java/io/spine/server/delivery/DeliveredMessagesCache.java
similarity index 94%
rename from server/src/main/java/io/spine/server/delivery/DeliveredMessages.java
rename to server/src/main/java/io/spine/server/delivery/DeliveredMessagesCache.java
index 70dfeb3c03a..4303bd0f1e5 100644
--- a/server/src/main/java/io/spine/server/delivery/DeliveredMessages.java
+++ b/server/src/main/java/io/spine/server/delivery/DeliveredMessagesCache.java
@@ -36,12 +36,12 @@
 /**
  * A cache of the messages locally delivered within the instance of {@link Delivery}.
  *
- * <p>The cache is limited in size, aiming to hunt down the only the duplicates of the recently
+ * <p>The cache is limited in size, aiming to hunt down only the duplicates of the recently
  * delivered messages. The idea behind it is that the messages were read locally anyway,
  * so as well their identifiers may be reused for deduplication instead of just wasting
  * the effort and feeding the garbage collector.
  */
-final class DeliveredMessages {
+final class DeliveredMessagesCache {
 
     private final Cache<DispatchingId, Timestamp> cache =
             CacheBuilder.newBuilder()
diff --git a/server/src/main/java/io/spine/server/delivery/Delivery.java b/server/src/main/java/io/spine/server/delivery/Delivery.java
index 1e808d3584a..5b3bbdd6f68 100644
--- a/server/src/main/java/io/spine/server/delivery/Delivery.java
+++ b/server/src/main/java/io/spine/server/delivery/Delivery.java
@@ -197,7 +197,7 @@
  * performing the actual message dispatching rely onto this knowledge and deduplicate
  * the messages prior to calling the target's endpoint.
  *
- * <p>Additionally, the {@code Delivery} provides a {@linkplain DeliveredMessages cache of recently
+ * <p>Additionally, the {@code Delivery} provides a {@linkplain DeliveredMessagesCache cache of recently
  * delivered messages}. Each instance of the {@code Conveyor} has an access to it and uses it
  * in deduplication procedures.
  *
@@ -298,7 +298,7 @@ public final class Delivery implements WithLogging {
     /**
      * The cache of the locally delivered messages.
      */
-    private final DeliveredMessages deliveredMessages;
+    private final DeliveredMessagesCache deliveredMessagesCache;
 
     /**
      * The maximum amount of messages to deliver within a {@link DeliveryStage}.
@@ -325,7 +325,7 @@ public final class Delivery implements WithLogging {
         this.pageSize = builder.getPageSize();
         this.deliveries = new InboxDeliveries();
         this.shardObservers = synchronizedList(new ArrayList<>());
-        this.deliveredMessages = new DeliveredMessages();
+        this.deliveredMessagesCache = new DeliveredMessagesCache();
     }
 
     /**
@@ -571,7 +571,7 @@ private ImmutableList<CatchUp> refreshCatchUpJobs() {
     private DeliveryStage deliverMessages(ImmutableList<InboxMessage> messages,
                                           ShardIndex index,
                                           Iterable<CatchUp> catchUpJobs) {
-        var conveyor = new Conveyor(messages, deliveredMessages);
+        var conveyor = new Conveyor(messages, deliveredMessagesCache);
         DeliveryAction action = new GroupByTargetAndDeliver(deliveries, monitor, conveyor);
         List<Station> stations = conveyorStationsFor(catchUpJobs, action);
         var stage = launch(conveyor, stations, index);
diff --git a/server/src/main/java/io/spine/server/entity/EntityLifecycle.java b/server/src/main/java/io/spine/server/entity/EntityLifecycle.java
index 2289bcb1cf5..9f39bdc28cf 100644
--- a/server/src/main/java/io/spine/server/entity/EntityLifecycle.java
+++ b/server/src/main/java/io/spine/server/entity/EntityLifecycle.java
@@ -114,7 +114,7 @@ public class EntityLifecycle {
     private final EventFilter eventFilter;
 
     /**
-     * The message ID of of the associated {@link Entity} state.
+     * The message ID of the associated {@link Entity} state.
      */
     private final MessageId entityId;
 
diff --git a/server/src/main/java/io/spine/server/integration/IntegrationBroker.java b/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
index 7c275ad5372..634cacd49dc 100644
--- a/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
+++ b/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
@@ -29,6 +29,7 @@
 import io.spine.annotation.Internal;
 import io.spine.core.BoundedContextName;
 import io.spine.server.BoundedContext;
+import io.spine.server.Closeable;
 import io.spine.server.ContextAware;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.event.EventDispatcher;
@@ -115,7 +116,7 @@
  * between the Contexts.
  */
 @Internal
-public final class IntegrationBroker implements ContextAware, AutoCloseable {
+public final class IntegrationBroker implements ContextAware, Closeable {
 
     private final SubscriberHub subscriberHub;
     private final PublisherHub publisherHub;
@@ -203,6 +204,11 @@ public void close() throws Exception {
         publisherHub.close();
     }
 
+    @Override
+    public boolean isOpen() {
+        return subscriberHub.isOpen();
+    }
+
     @Override
     public String toString() {
         return "`IntegrationBroker` of <" + contextName.getValue() + '>';
diff --git a/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java b/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
index d10ca679b3d..d5c78e2e74f 100644
--- a/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
+++ b/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
@@ -64,17 +64,18 @@ static TypeRegistry newInstance() {
         return new InMemoryTypeRegistry();
     }
 
-    @SuppressWarnings("ChainOfInstanceofChecks")
     @Override
+    @SuppressWarnings("ChainOfInstanceofChecks")
     public <I, E extends Entity<I, ?>> void register(Repository<I, E> repository) {
         var entityType = repository.entityStateType();
 
         if (repository instanceof QueryableRepository) {
             @SuppressWarnings("unchecked")  /* Guaranteed by the `QueryableRepository` contract. */
-            var recordRepo = (QueryableRepository<I, ?>) repository;
+                    var recordRepo = (QueryableRepository<I, ?>) repository;
             repositories.put(entityType, recordRepo);
         }
         if (repository instanceof AggregateRepository) {
+            @SuppressWarnings("unchecked")
             AggregateRepository<I, ?, ?> aggRepository = (AggregateRepository<I, ?, ?>) repository;
             aggregateTypes.add(aggRepository.entityStateType());
         }
@@ -98,6 +99,11 @@ public ImmutableSet<TypeUrl> allTypes() {
         return ImmutableSet.copyOf(repositories.keySet());
     }
 
+    @Override
+    public boolean isOpen() {
+        return !repositories.isEmpty();
+    }
+
     @Override
     public void close() {
         repositories.clear();
diff --git a/server/src/main/java/io/spine/server/stand/Stand.java b/server/src/main/java/io/spine/server/stand/Stand.java
index f4763e382b0..68573b4751c 100644
--- a/server/src/main/java/io/spine/server/stand/Stand.java
+++ b/server/src/main/java/io/spine/server/stand/Stand.java
@@ -41,6 +41,7 @@
 import io.spine.core.Response;
 import io.spine.core.Responses;
 import io.spine.protobuf.AnyPacker;
+import io.spine.server.Closeable;
 import io.spine.server.EventProducer;
 import io.spine.server.Identity;
 import io.spine.server.bus.Listener;
@@ -83,8 +84,7 @@
  * @see <a href="https://spine.io/docs/concepts/diagrams/spine-architecture-diagram-full-screen.html">
  *     Spine Architecture Diagram</a>
  */
-@SuppressWarnings("OverlyCoupledClass")
-public class Stand implements AutoCloseable {
+public class Stand implements Closeable {
 
     /**
      * Used to return an empty result collection for {@link Query}.
@@ -371,6 +371,11 @@ public void registerTypeSupplier(EventProducer producer) {
         eventRegistry.register(producer);
     }
 
+    @Override
+    public boolean isOpen() {
+        return typeRegistry.isOpen();
+    }
+
     /**
      * Closes the {@code Stand} performing necessary cleanups.
      */
diff --git a/server/src/main/java/io/spine/server/stand/TypeRegistry.java b/server/src/main/java/io/spine/server/stand/TypeRegistry.java
index c9578c81ac2..e3eaace4ba9 100644
--- a/server/src/main/java/io/spine/server/stand/TypeRegistry.java
+++ b/server/src/main/java/io/spine/server/stand/TypeRegistry.java
@@ -26,6 +26,7 @@
 package io.spine.server.stand;
 
 import com.google.common.collect.ImmutableSet;
+import io.spine.server.Closeable;
 import io.spine.server.entity.Entity;
 import io.spine.server.entity.QueryableRepository;
 import io.spine.server.entity.RecordBasedRepository;
@@ -40,7 +41,7 @@
  * <p>In addition to types, manages the information about the {@linkplain Repository repositories}
  * for the objects of known types.
  */
-interface TypeRegistry extends AutoCloseable {
+interface TypeRegistry extends Closeable {
 
     /**
      * Registers a {@linkplain Repository repository} of objects and
diff --git a/server/src/main/java/io/spine/server/transport/ChannelHub.java b/server/src/main/java/io/spine/server/transport/ChannelHub.java
index 4e002e485a0..c3fea4de5df 100644
--- a/server/src/main/java/io/spine/server/transport/ChannelHub.java
+++ b/server/src/main/java/io/spine/server/transport/ChannelHub.java
@@ -26,6 +26,7 @@
 package io.spine.server.transport;
 
 import io.spine.annotation.SPI;
+import io.spine.server.Closeable;
 
 import java.util.Map;
 import java.util.Set;
@@ -45,7 +46,7 @@
  *         the type of grouped channels
  */
 @SPI
-public abstract class ChannelHub<C extends MessageChannel> implements AutoCloseable {
+public abstract class ChannelHub<C extends MessageChannel> implements Closeable {
 
     private final TransportFactory transportFactory;
     private final Map<ChannelId, C> channels = new ConcurrentHashMap<>();
@@ -112,6 +113,11 @@ private Set<ChannelId> detectStale() {
         return toRemove;
     }
 
+    @Override
+    public boolean isOpen() {
+        return !channels.isEmpty();
+    }
+
     @Override
     public void close() throws Exception {
         for (var channel : channels.values()) {
diff --git a/server/src/test/java/io/spine/server/delivery/AbstractStationTest.java b/server/src/test/java/io/spine/server/delivery/AbstractStationTest.java
index 18da6374862..206e6fb7982 100644
--- a/server/src/test/java/io/spine/server/delivery/AbstractStationTest.java
+++ b/server/src/test/java/io/spine/server/delivery/AbstractStationTest.java
@@ -65,7 +65,7 @@ abstract class AbstractStationTest {
     void doNothingOnEmptyConveyor() {
         var action = new MemoizingAction();
         var station = newStation(action);
-        var emptyConveyor = new Conveyor(new ArrayList<>(), new DeliveredMessages());
+        var emptyConveyor = new Conveyor(new ArrayList<>(), new DeliveredMessagesCache());
 
         var result = station.process(emptyConveyor);
         assertDeliveredCount(result, 0);
diff --git a/server/src/test/java/io/spine/server/delivery/CatchUpStationTest.java b/server/src/test/java/io/spine/server/delivery/CatchUpStationTest.java
index 0ab9d958def..ebb619eb6d2 100644
--- a/server/src/test/java/io/spine/server/delivery/CatchUpStationTest.java
+++ b/server/src/test/java/io/spine/server/delivery/CatchUpStationTest.java
@@ -73,7 +73,7 @@ void removeLiveMessagesIfCatchUpStarted() {
         var differentTarget = delivered(targetTwo, type);
         var conveyor = new Conveyor(
                 ImmutableList.of(toDeliver, anotherToDeliver, delivered, differentTarget),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         var job = catchUpJob(type, IN_PROGRESS, currentTime(), ImmutableList.of(targetOne));
@@ -104,7 +104,7 @@ void matchAndRunDeliveryAction() {
         var initialContents =
                 ImmutableList.of(toCatchUp, anotherToCatchUp, duplicateCopy,
                                  alreadyDelivered, differentTarget);
-        var conveyor = new Conveyor(initialContents, new DeliveredMessages());
+        var conveyor = new Conveyor(initialContents, new DeliveredMessagesCache());
 
         var job = catchUpJob(type, IN_PROGRESS, currentTime(), ImmutableList.of(targetOne));
         var station = new CatchUpStation(MemoizingAction.empty(), ImmutableList.of(job));
@@ -138,7 +138,7 @@ void markLiveMessagesCatchUpIfJobFinalizing() {
         var differentTarget = delivered(targetTwo, type);
         var conveyor = new Conveyor(
                 ImmutableList.of(toDeliver, anotherToDeliver, delivered, differentTarget),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         var job = catchUpJob(type, FINALIZING, currentTime(), ImmutableList.of(targetOne));
@@ -167,7 +167,7 @@ void deduplicateAndDeliverWhenJobCompleted() {
         var conveyor = new Conveyor(
                 ImmutableList.of(toCatchUp, moreToCatchUp, toDeliver,
                                  duplicateToCatchUp, duplicateToDeliver),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         var job = catchUpJob(type, COMPLETED, currentTime(), ImmutableList.of(targetOne));
@@ -207,7 +207,7 @@ void sortCatchUpMessagesBeforeCallingToAction() {
         var toCatchUp4 = catchingUp(targetOne, type, now);
         var conveyor = new Conveyor(
                 ImmutableList.of(toCatchUp3, toCatchUp2, toCatchUp4, toCatchUp1),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         var job = catchUpJob(type, IN_PROGRESS, currentTime(), ImmutableList.of(targetOne));
diff --git a/server/src/test/java/io/spine/server/delivery/CleanupStationTest.java b/server/src/test/java/io/spine/server/delivery/CleanupStationTest.java
index 44c7affda85..526cead96e7 100644
--- a/server/src/test/java/io/spine/server/delivery/CleanupStationTest.java
+++ b/server/src/test/java/io/spine/server/delivery/CleanupStationTest.java
@@ -56,7 +56,7 @@ void removeDeliveredMessages() {
         var toDeliver = toDeliver(targetOne, type);
         var conveyor = new Conveyor(
                 ImmutableList.of(delivered, deliveredToAnotherTarget, catchingUp, toDeliver),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         Station station = new CleanupStation();
@@ -85,7 +85,7 @@ void considerKeepUntilWhenRemoving() {
         );
         var conveyor = new Conveyor(
                 ImmutableList.of(deliveredKeepTillFuture, deliveredKeepUntilPastTime),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         Station station = new CleanupStation();
diff --git a/server/src/test/java/io/spine/server/delivery/LiveDeliveryStationTest.java b/server/src/test/java/io/spine/server/delivery/LiveDeliveryStationTest.java
index 0a593e35eea..8e1b9d0e85c 100644
--- a/server/src/test/java/io/spine/server/delivery/LiveDeliveryStationTest.java
+++ b/server/src/test/java/io/spine/server/delivery/LiveDeliveryStationTest.java
@@ -66,7 +66,7 @@ void runDeliveryActionForToDeliver() {
         var initialContents =
                 ImmutableList.of(toDeliver, anotherToDeliver, differentTarget,
                                  alreadyDelivered, toCatchUp);
-        var conveyor = new Conveyor(initialContents, new DeliveredMessages());
+        var conveyor = new Conveyor(initialContents, new DeliveredMessagesCache());
 
         var action = MemoizingAction.empty();
         Station station = new LiveDeliveryStation(action, noWindow());
@@ -104,7 +104,7 @@ void removeDuplicates() {
         var initialContents =
                 ImmutableList.of(toDeliver, duplicate, anotherDuplicate,
                                  alreadyDelivered, duplicateOfDelivered, toCatchUp);
-        var conveyor = new Conveyor(initialContents, new DeliveredMessages());
+        var conveyor = new Conveyor(initialContents, new DeliveredMessagesCache());
 
         var action = MemoizingAction.empty();
         Station station = new LiveDeliveryStation(action, noWindow());
@@ -143,7 +143,7 @@ void sort() {
         var toDeliver4 = toDeliver(targetTwo, type, now);
         var conveyor = new Conveyor(
                 ImmutableList.of(toDeliver2, toDeliver3, toDeliver4, toDeliver1),
-                new DeliveredMessages()
+                new DeliveredMessagesCache()
         );
 
         var action = MemoizingAction.empty();
@@ -167,7 +167,7 @@ void keepMessagesForLongerIfDeduplicationWindowSet() {
 
         var initialContents =
                 ImmutableList.of(toDeliver, differentTarget, alreadyDelivered, toCatchUp);
-        var conveyor = new Conveyor(initialContents, new DeliveredMessages());
+        var conveyor = new Conveyor(initialContents, new DeliveredMessagesCache());
 
         Station station = new LiveDeliveryStation(MemoizingAction.empty(), fromSeconds(100));
         var result = station.process(conveyor);
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 80816f2f825..56c7ee5adb0 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -58,12 +58,14 @@
 import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
@@ -73,7 +75,6 @@
 import static io.spine.grpc.StreamObservers.memoizingObserver;
 import static io.spine.server.entity.model.EntityClass.stateClassOf;
 import static io.spine.testing.server.blackbox.Actor.defaultActor;
-import static io.spine.util.Exceptions.illegalStateWithCauseOf;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.synchronizedSet;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -91,12 +92,12 @@ public abstract class BlackBox implements WithLogging, Closeable {
     /**
      * The context under the test.
      */
-    private final BoundedContext context;
+    private @MonotonicNonNull BoundedContext context;
 
     /**
      * A factory of {@link Client}s which send requests to this context.
      */
-    private final ClientFactory clientFactory;
+    private @MonotonicNonNull ClientFactory clientFactory;
 
     /**
      * Collects all commands, including posted to the context during its setup or
@@ -140,35 +141,61 @@ public abstract class BlackBox implements WithLogging, Closeable {
      * Creates new instance obtaining configuration parameters from the passed builder.
      */
     public static BlackBox from(BoundedContextBuilder builder) {
+        var supplier = initLazilyFrom(builder, null);
+        var ignored = builder.build();
+        return supplier.get();
+    }
+
+    /**
+     * Creates new instance obtaining configuration parameters from the passed builder.
+     *
+     * @param builder
+     *         the builder of the context under the test
+     * @param customCleanup
+     *         if not `null`, the procedure to be executed in {@link #close()}
+     *         <em>before</em> closing other resources of the blackbox
+     */
+    public static BlackBox from(BoundedContextBuilder builder, @Nullable Runnable customCleanup) {
         var result =
                 builder.isMultitenant()
-                ? new MtBlackBox(builder)
-                : new StBlackBox(builder);
+                ? new MtBlackBox(builder, customCleanup)
+                : new StBlackBox(builder, customCleanup);
         return result;
     }
 
-    BlackBox(BoundedContextBuilder builder) {
+    public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder,
+                                                    @Nullable Runnable customCleanup) {
+        var result = new AtomicReference<BlackBox>();
+        builder.setOnBeforeBuild(configuredBuilder -> {
+            var box = builder.isMultitenant()
+                      ? new MtBlackBox(configuredBuilder, customCleanup)
+                      : new StBlackBox(configuredBuilder, customCleanup);
+            result.set(box);
+        });
+        return result::get;
+    }
+
+    BlackBox(BoundedContextBuilder builder, @Nullable Runnable customCleanup) {
         super();
         this.commands = new CommandCollector();
         this.postedCommands = synchronizedSet(new HashSet<>());
         this.events = new EventCollector();
         this.postedEvents = synchronizedSet(new HashSet<>());
         this.failedHandlerGuard = new FailedHandlerGuard();
-        var wiredCopy = wiredCopyOf(builder);
-        this.context = wiredCopy.build();
         this.actor = defaultActor();
-        this.clientFactory = new ClientFactory(context);
-    }
-
-    private BoundedContextBuilder wiredCopyOf(BoundedContextBuilder builder) {
-        var result = builder.testingCopy();
-        result.addCommandListener(commands)
+        builder.addCommandListener(commands)
               .addEventListener(events)
               .addEventDispatcher(failedHandlerGuard)
-              .addEventDispatcher(new UnsupportedCommandGuard(result.name()
-                                                                    .getValue()))
+              .addEventDispatcher(new UnsupportedCommandGuard(builder.name().getValue()))
               .addEventDispatcher(DiagnosticLog.instance());
-        return result;
+        if(customCleanup != null) {
+            builder.setOnBeforeClose((ignored) -> customCleanup.run());
+        }
+        var created = this;
+        builder.setOnBuild(context -> {
+            created.clientFactory = new ClientFactory(context);
+            created.context = context;
+        });
     }
 
     /**
@@ -478,20 +505,13 @@ private BlackBoxSetup setup() {
      */
     @Override
     public final void close() {
-        if (!isOpen()) {
-            return;
-        }
-        try {
-            context.close();
-            clientFactory.close();
-        } catch (Exception e) {
-            throw illegalStateWithCauseOf(e);
-        }
+        context.closeIfOpen();
+        clientFactory.closeIfOpen();
     }
 
     @Override
     public boolean isOpen() {
-        return context().isOpen();
+        return context.isOpen() || clientFactory.isOpen();
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
index 2298fc3f114..eeef920c73a 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
@@ -52,8 +52,8 @@ final class MtBlackBox extends BlackBox {
     /**
      * Creates a new multi-tenant instance.
      */
-    MtBlackBox(BoundedContextBuilder b) {
-        super(b);
+    MtBlackBox(BoundedContextBuilder b, @Nullable Runnable customCleanup) {
+        super(b, customCleanup);
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
index 9381d39edcd..2d8c2ff45fb 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
@@ -33,6 +33,7 @@
 import io.spine.core.TenantId;
 import io.spine.server.BoundedContextBuilder;
 import io.spine.testing.client.TestActorRequestFactory;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 import static com.google.protobuf.TextFormat.shortDebugString;
 import static io.spine.util.Exceptions.newIllegalStateException;
@@ -42,8 +43,8 @@
  */
 final class StBlackBox extends BlackBox {
 
-    StBlackBox(BoundedContextBuilder b) {
-        super(b);
+    StBlackBox(BoundedContextBuilder b, @Nullable Runnable customCleanup) {
+        super(b, customCleanup);
     }
 
     @Override

From 3c809c4e92ccb41665d4a443259eb2f698e5260d Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Sat, 28 Oct 2023 16:30:04 +0100
Subject: [PATCH 02/32] Remove redundant parameter

---
 .../testing/server/blackbox/BlackBox.java     | 33 +++++--------------
 .../testing/server/blackbox/MtBlackBox.java   |  4 +--
 .../testing/server/blackbox/StBlackBox.java   |  4 +--
 3 files changed, 12 insertions(+), 29 deletions(-)

diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 56c7ee5adb0..9a1699cf1e0 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -141,41 +141,27 @@ public abstract class BlackBox implements WithLogging, Closeable {
      * Creates new instance obtaining configuration parameters from the passed builder.
      */
     public static BlackBox from(BoundedContextBuilder builder) {
-        var supplier = initLazilyFrom(builder, null);
+        var supplier = initLazilyFrom(builder);
         var ignored = builder.build();
         return supplier.get();
     }
 
     /**
-     * Creates new instance obtaining configuration parameters from the passed builder.
-     *
-     * @param builder
-     *         the builder of the context under the test
-     * @param customCleanup
-     *         if not `null`, the procedure to be executed in {@link #close()}
-     *         <em>before</em> closing other resources of the blackbox
-     */
-    public static BlackBox from(BoundedContextBuilder builder, @Nullable Runnable customCleanup) {
-        var result =
-                builder.isMultitenant()
-                ? new MtBlackBox(builder, customCleanup)
-                : new StBlackBox(builder, customCleanup);
-        return result;
-    }
-
-    public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder,
-                                                    @Nullable Runnable customCleanup) {
+     * Arranged a delayed creation of new {@code Blackbox} obtaining configuration parameters
+     * from the passed builder.
+     */
+    public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder) {
         var result = new AtomicReference<BlackBox>();
         builder.setOnBeforeBuild(configuredBuilder -> {
             var box = builder.isMultitenant()
-                      ? new MtBlackBox(configuredBuilder, customCleanup)
-                      : new StBlackBox(configuredBuilder, customCleanup);
+                      ? new MtBlackBox(configuredBuilder)
+                      : new StBlackBox(configuredBuilder);
             result.set(box);
         });
         return result::get;
     }
 
-    BlackBox(BoundedContextBuilder builder, @Nullable Runnable customCleanup) {
+    BlackBox(BoundedContextBuilder builder) {
         super();
         this.commands = new CommandCollector();
         this.postedCommands = synchronizedSet(new HashSet<>());
@@ -188,9 +174,6 @@ public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder,
               .addEventDispatcher(failedHandlerGuard)
               .addEventDispatcher(new UnsupportedCommandGuard(builder.name().getValue()))
               .addEventDispatcher(DiagnosticLog.instance());
-        if(customCleanup != null) {
-            builder.setOnBeforeClose((ignored) -> customCleanup.run());
-        }
         var created = this;
         builder.setOnBuild(context -> {
             created.clientFactory = new ClientFactory(context);
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
index eeef920c73a..2298fc3f114 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
@@ -52,8 +52,8 @@ final class MtBlackBox extends BlackBox {
     /**
      * Creates a new multi-tenant instance.
      */
-    MtBlackBox(BoundedContextBuilder b, @Nullable Runnable customCleanup) {
-        super(b, customCleanup);
+    MtBlackBox(BoundedContextBuilder b) {
+        super(b);
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
index 2d8c2ff45fb..6ed954ed7c3 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
@@ -43,8 +43,8 @@
  */
 final class StBlackBox extends BlackBox {
 
-    StBlackBox(BoundedContextBuilder b, @Nullable Runnable customCleanup) {
-        super(b, customCleanup);
+    StBlackBox(BoundedContextBuilder b) {
+        super(b);
     }
 
     @Override

From 5f060470392d6aebf6453e62f8be96339fb8e7ab Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Sat, 28 Oct 2023 16:51:30 +0100
Subject: [PATCH 03/32] Fix code layout

---
 .../java/io/spine/testing/server/blackbox/BlackBox.java   | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 9a1699cf1e0..eedbd2ee1b2 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -170,10 +170,10 @@ public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder) {
         this.failedHandlerGuard = new FailedHandlerGuard();
         this.actor = defaultActor();
         builder.addCommandListener(commands)
-              .addEventListener(events)
-              .addEventDispatcher(failedHandlerGuard)
-              .addEventDispatcher(new UnsupportedCommandGuard(builder.name().getValue()))
-              .addEventDispatcher(DiagnosticLog.instance());
+               .addEventListener(events)
+               .addEventDispatcher(failedHandlerGuard)
+               .addEventDispatcher(new UnsupportedCommandGuard(builder.name().getValue()))
+               .addEventDispatcher(DiagnosticLog.instance());
         var created = this;
         builder.setOnBuild(context -> {
             created.clientFactory = new ClientFactory(context);

From 3d61b40c98119cffe0d72db6f85ff49e791eb546 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Sat, 28 Oct 2023 16:51:44 +0100
Subject: [PATCH 04/32] Bump version -> `2.0.0-SNAPSHOT.161`

---
 license-report.md  | 24 ++++++++++++------------
 pom.xml            |  2 +-
 version.gradle.kts |  2 +-
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/license-report.md b/license-report.md
index 6330185004a..69df68ab262 100644
--- a/license-report.md
+++ b/license-report.md
@@ -1,6 +1,6 @@
 
 
-# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -800,12 +800,12 @@
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:07 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine:spine-core:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine:spine-core:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -1565,12 +1565,12 @@ This report was generated on **Fri Oct 13 00:27:07 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:08 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine:spine-server:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine:spine-server:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -2378,12 +2378,12 @@ This report was generated on **Fri Oct 13 00:27:08 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:08 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-client:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine.tools:spine-testutil-client:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -3311,12 +3311,12 @@ This report was generated on **Fri Oct 13 00:27:08 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:09 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-core:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine.tools:spine-testutil-core:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -4244,12 +4244,12 @@ This report was generated on **Fri Oct 13 00:27:09 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:10 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-server:2.0.0-SNAPSHOT.160`
+# Dependencies of `io.spine.tools:spine-testutil-server:2.0.0-SNAPSHOT.161`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -5225,4 +5225,4 @@ This report was generated on **Fri Oct 13 00:27:10 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Fri Oct 13 00:27:10 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
+This report was generated on **Sat Oct 28 16:50:19 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index ef23dc312fb..c044183239c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,7 +10,7 @@ all modules and does not describe the project structure per-subproject.
  -->
 <groupId>io.spine</groupId>
 <artifactId>spine-core-java</artifactId>
-<version>2.0.0-SNAPSHOT.160</version>
+<version>2.0.0-SNAPSHOT.161</version>
 
 <inceptionYear>2015</inceptionYear>
 
diff --git a/version.gradle.kts b/version.gradle.kts
index 9ede62134fb..6549ecbd082 100644
--- a/version.gradle.kts
+++ b/version.gradle.kts
@@ -29,4 +29,4 @@
  *
  * For versions of Spine-based dependencies, please see [io.spine.internal.dependency.Spine].
  */
-val versionToPublish: String by extra("2.0.0-SNAPSHOT.160")
+val versionToPublish: String by extra("2.0.0-SNAPSHOT.161")

From e0fc1fc897a9d9ee784cb1258d1997e5eca112ad Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Sun, 29 Oct 2023 19:22:01 +0000
Subject: [PATCH 05/32] Introduce `Probe`

---
 .../testing/server/blackbox/BlackBox.java     | 48 ++++--------
 .../server/blackbox/BlackBoxSetup.java        |  2 +-
 .../server/blackbox/CommandCollector.java     |  2 +-
 .../server/blackbox/EventCollector.java       |  2 +-
 .../server/blackbox/FailedHandlerGuard.java   |  2 +-
 .../server/blackbox/MessageCollector.java     |  2 +-
 .../spine/testing/server/blackbox/Probe.java  | 76 +++++++++++++++++++
 7 files changed, 96 insertions(+), 38 deletions(-)
 create mode 100644 testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java

diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index eedbd2ee1b2..0a6ad44f652 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -94,16 +94,20 @@ public abstract class BlackBox implements WithLogging, Closeable {
      */
     private @MonotonicNonNull BoundedContext context;
 
+    /**
+     * The probe inserted into the context under the test.
+     */
+    private final Probe probe;
+
     /**
      * A factory of {@link Client}s which send requests to this context.
      */
     private @MonotonicNonNull ClientFactory clientFactory;
 
     /**
-     * Collects all commands, including posted to the context during its setup or
-     * generated by the entities in response to posted or generated events or commands.
+     * Information about the current user and the time-zone.
      */
-    private final CommandCollector commands;
+    private Actor actor;
 
     /**
      * Commands received by this instance and posted to Command Bus during the test setup.
@@ -113,12 +117,6 @@ public abstract class BlackBox implements WithLogging, Closeable {
      */
     private final Set<Command> postedCommands;
 
-    /**
-     * Collects all events, including posted to the context during its setup or
-     * generated by the entities in response to posted or generated events or commands.
-     */
-    private final EventCollector events;
-
     /**
      * Events received by this instance and posted to the Event Bus during the test setup.
      *
@@ -127,16 +125,6 @@ public abstract class BlackBox implements WithLogging, Closeable {
      */
     private final Set<Event> postedEvents;
 
-    /**
-     * Handles runtime exceptions thrown from signal handlers.
-     */
-    private final FailedHandlerGuard failedHandlerGuard;
-
-    /**
-     * Information about the current user and the time-zone.
-     */
-    private Actor actor;
-
     /**
      * Creates new instance obtaining configuration parameters from the passed builder.
      */
@@ -163,22 +151,16 @@ public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder) {
 
     BlackBox(BoundedContextBuilder builder) {
         super();
-        this.commands = new CommandCollector();
-        this.postedCommands = synchronizedSet(new HashSet<>());
-        this.events = new EventCollector();
-        this.postedEvents = synchronizedSet(new HashSet<>());
-        this.failedHandlerGuard = new FailedHandlerGuard();
-        this.actor = defaultActor();
-        builder.addCommandListener(commands)
-               .addEventListener(events)
-               .addEventDispatcher(failedHandlerGuard)
-               .addEventDispatcher(new UnsupportedCommandGuard(builder.name().getValue()))
-               .addEventDispatcher(DiagnosticLog.instance());
+        this.probe = new Probe();
+        probe.installIn(builder);
         var created = this;
         builder.setOnBuild(context -> {
             created.clientFactory = new ClientFactory(context);
             created.context = context;
         });
+        this.actor = defaultActor();
+        this.postedCommands = synchronizedSet(new HashSet<>());
+        this.postedEvents = synchronizedSet(new HashSet<>());
     }
 
     /**
@@ -221,7 +203,7 @@ public final BlackBox in(ZoneId zoneId) {
      */
     @CanIgnoreReturnValue
     public final BlackBox tolerateFailures() {
-        failedHandlerGuard.tolerateFailures();
+        probe.failedHandlerGuard().tolerateFailures();
         return this;
     }
 
@@ -513,7 +495,7 @@ public boolean isOpen() {
     private ImmutableList<Command> commands() {
         var wasNotReceived =
                 ((Predicate<Command>) postedCommands::contains).negate();
-        return select(this.commands)
+        return select(probe.commands())
                 .stream()
                 .filter(wasNotReceived)
                 .collect(toImmutableList());
@@ -548,7 +530,7 @@ private ImmutableList<Event> events() {
      */
     @VisibleForTesting
     final ImmutableList<Event> allEvents() {
-        return select(this.events);
+        return select(probe.events());
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBoxSetup.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBoxSetup.java
index 437875c97f1..62195d18727 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBoxSetup.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBoxSetup.java
@@ -54,7 +54,7 @@
 import static java.util.stream.Collectors.toList;
 
 /**
- * A class which sets up a {@link BlackBox}.
+ * A class which configures a test environment in which {@link BlackBox} is used.
  *
  * <p>The setup may involve:
  * <ul>
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java
index 015dd770425..3a91478e4e7 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java
@@ -33,5 +33,5 @@
 /**
  * Remembers commands posted to a Command Bus.
  */
-final class CommandCollector extends MessageCollector<CommandId, Command, CommandEnvelope> {
+public final class CommandCollector extends MessageCollector<CommandId, Command, CommandEnvelope> {
 }
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java
index 1812d9faf1f..92872356b6e 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java
@@ -33,5 +33,5 @@
 /**
  * Remembers events posted to an Event Bus.
  */
-final class EventCollector extends MessageCollector<EventId, Event, EventEnvelope> {
+public final class EventCollector extends MessageCollector<EventId, Event, EventEnvelope> {
 }
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java
index 634662b5924..d62bba67018 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java
@@ -44,7 +44,7 @@
  * Performs logging of failed signals handlers or fails the test
  * depending upon the current context exception tolerance.
  */
-final class FailedHandlerGuard extends AbstractEventSubscriber implements DiagnosticLogging {
+public final class FailedHandlerGuard extends AbstractEventSubscriber implements DiagnosticLogging {
 
     private HandlerFailureTolerance tolerance = HandlerFailureTolerance.RAISE_AND_FAIL;
 
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java
index 3e36df09dc7..d5df7c42463 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java
@@ -57,7 +57,7 @@
  * @param <E>
  *         the type of the message envelopes
  */
-abstract class MessageCollector<I extends SignalId,
+public abstract class MessageCollector<I extends SignalId,
                                 T extends Signal<I, ?, ?>,
                                 E extends MessageEnvelope<I, T, ?>>
         implements Listener<E> {
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java
new file mode 100644
index 00000000000..b2750bda458
--- /dev/null
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.testing.server.blackbox;
+
+import io.spine.server.BoundedContextBuilder;
+
+public class Probe {
+
+    /**
+     * Collects all commands, including posted to the context during its setup or
+     * generated by the entities in response to posted or generated events or commands.
+     */
+    private final CommandCollector commands;
+
+    /**
+     * Collects all events, including posted to the context during its setup or
+     * generated by the entities in response to posted or generated events or commands.
+     */
+    private final EventCollector events;
+
+    /**
+     * Handles runtime exceptions thrown from signal handlers.
+     */
+    private final FailedHandlerGuard failedHandlerGuard;
+
+    Probe() {
+        this.commands = new CommandCollector();
+        this.events = new EventCollector();
+        this.failedHandlerGuard = new FailedHandlerGuard();
+    }
+
+    public CommandCollector commands() {
+        return commands;
+    }
+
+    public EventCollector events() {
+        return events;
+    }
+
+    public FailedHandlerGuard failedHandlerGuard() {
+        return failedHandlerGuard;
+    }
+
+    public void installIn(BoundedContextBuilder builder) {
+        builder.addCommandListener(commands())
+               .addEventListener(events())
+               .addEventDispatcher(failedHandlerGuard())
+               .addEventDispatcher(new UnsupportedCommandGuard(builder.name()
+                                                                      .getValue()))
+               .addEventDispatcher(DiagnosticLog.instance());
+    }
+}

From e05f1627d2262541165bb7d3973da505852bf049 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Mon, 30 Oct 2023 14:31:33 +0000
Subject: [PATCH 06/32] Teach `BoundedContext` swallowing `Probe`

---
 .../java/io/spine/server/BoundedContext.java  | 102 ++++++++++++++++--
 .../java/io/spine/server/ContextAware.java    |  16 ++-
 .../io/spine/server/ServerEnvironment.java    |   2 +-
 .../main/java/io/spine/server/bus/Bus.java    |  32 ++++--
 .../server/bus/DelegatingDispatcher.java      |  42 ++++++++
 .../spine/server/bus/DispatcherDelegate.java  |  35 ++++++
 .../spine/server/bus/DispatcherRegistry.java  |  12 +++
 .../java/io/spine/server/bus/Listeners.java   |  18 +++-
 .../commandbus/CommandDispatcherDelegate.java |   6 +-
 .../DelegatingCommandDispatcher.java          |  10 +-
 .../event/DelegatingEventDispatcher.java      |  10 +-
 .../server/event/EventDispatcherDelegate.java |   5 +-
 .../io/spine/system/server/SystemContext.java |   4 +-
 .../AggregateHistoryTruncationTest.java       |  86 +++++++--------
 .../testing/server/blackbox/BlackBox.java     |   5 +-
 .../testing/server/blackbox/MtBlackBox.java   |   2 +
 .../testing/server/blackbox/StBlackBox.java   |   3 +-
 .../testing/server/blackbox/package-info.java |   2 +-
 .../{ => probe}/CommandCollector.java         |   4 +-
 .../blackbox/{ => probe}/DiagnosticLog.java   |   4 +-
 .../{ => probe}/DiagnosticLogging.java        |   2 +-
 .../blackbox/{ => probe}/EventCollector.java  |   4 +-
 .../{ => probe}/FailedHandlerGuard.java       |   6 +-
 .../{ => probe}/HandlerFailureTolerance.java  |   6 +-
 .../{ => probe}/MessageCollector.java         |   4 +-
 .../server/blackbox/{ => probe}/Probe.java    |  57 ++++++++--
 .../{ => probe}/UnsupportedCommandGuard.java  |   5 +-
 .../server/blackbox/probe/package-info.java   |  37 +++++++
 .../blackbox/UnsupportedCommandGuardTest.java |  75 -------------
 .../given/BbProjectFailerProcess.java         |   3 +-
 .../{ => probe}/DiagnosticLogTest.java        |   4 +-
 .../{ => probe}/DiagnosticLoggingTest.java    |   5 +-
 .../{ => probe}/FailedHandlerGuardTest.java   |   4 +-
 .../probe/UnsupportedCommandGuardSpec.kt      |  70 ++++++++++++
 34 files changed, 500 insertions(+), 182 deletions(-)
 create mode 100644 server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
 create mode 100644 server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/CommandCollector.java (93%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/DiagnosticLog.java (97%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/DiagnosticLogging.java (98%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/EventCollector.java (93%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/FailedHandlerGuard.java (98%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/HandlerFailureTolerance.java (91%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/MessageCollector.java (97%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/Probe.java (62%)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/{ => probe}/UnsupportedCommandGuard.java (97%)
 create mode 100644 testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
 delete mode 100644 testutil-server/src/test/java/io/spine/testing/server/blackbox/UnsupportedCommandGuardTest.java
 rename testutil-server/src/test/java/io/spine/testing/server/blackbox/{ => probe}/DiagnosticLogTest.java (98%)
 rename testutil-server/src/test/java/io/spine/testing/server/blackbox/{ => probe}/DiagnosticLoggingTest.java (95%)
 rename testutil-server/src/test/java/io/spine/testing/server/blackbox/{ => probe}/FailedHandlerGuardTest.java (96%)
 create mode 100644 testutil-server/src/test/kotlin/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuardSpec.kt

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 6c3e4225c25..f2bc047ff60 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -34,6 +34,7 @@
 import io.spine.option.EntityOption.Visibility;
 import io.spine.server.aggregate.AggregateRootDirectory;
 import io.spine.server.aggregate.ImportBus;
+import io.spine.server.bus.Listener;
 import io.spine.server.commandbus.CommandBus;
 import io.spine.server.commandbus.CommandDispatcher;
 import io.spine.server.commandbus.CommandDispatcherDelegate;
@@ -52,6 +53,8 @@
 import io.spine.server.storage.StorageFactory;
 import io.spine.server.tenant.TenantIndex;
 import io.spine.server.trace.TracerFactory;
+import io.spine.server.type.CommandEnvelope;
+import io.spine.server.type.EventEnvelope;
 import io.spine.system.server.SystemClient;
 import io.spine.system.server.SystemContext;
 import io.spine.type.TypeName;
@@ -69,7 +72,7 @@
 /**
  * A logical and structural boundary of a model.
  *
- * <p>Logically, a Bounded Context represents a sub-system built to be described with the same
+ * <p>Logically, a Bounded Context represents a subsystem built to be described with the same
  * Ubiquitous Language. Any term within a single bounded context has a single meaning and may or
  * may not map to another term in the language of another Bounded Context.
  *
@@ -120,11 +123,16 @@ public abstract class BoundedContext
     /** The index of tenants having data in this context. */
     private final TenantIndex tenantIndex;
 
-    /** Provides access to internally-used features of the context. */
+    /** Provides access to internally used features of the context. */
     private final InternalAccess internalAccess;
 
     private final @Nullable Consumer<BoundedContext> onBeforeClose;
 
+    /**
+     * The currently installed probe.
+     */
+    private @Nullable Probe probe;
+
     /**
      * Creates new instance.
      *
@@ -149,7 +157,6 @@ protected BoundedContext(BoundedContextBuilder builder) {
         this.aggregateRootDirectory = builder.aggregateRootDirectory();
         this.internalAccess = new InternalAccess();
         this.onBeforeClose = builder.getOnBeforeClose();
-
     }
 
     /**
@@ -238,6 +245,7 @@ protected final void register(Repository<?, ?> repository) {
      *
      * @see #registerCommandDispatcher(CommandDispatcherDelegate)
      */
+    @SuppressWarnings("WeakerAccess") // This class is effectively `sealed`, so this is stricter.
     protected void registerCommandDispatcher(CommandDispatcher dispatcher) {
         checkNotNull(dispatcher);
         registerIfAware(dispatcher);
@@ -262,6 +270,13 @@ private void registerCommandDispatcher(CommandDispatcherDelegate dispatcher) {
         }
     }
 
+    private void unregisterCommandDispatcher(CommandDispatcherDelegate dispatcher) {
+        checkNotNull(dispatcher);
+        if (dispatcher.dispatchesCommands()) {
+            commandBus().unregister(dispatcher);
+        }
+    }
+
     /**
      * Registering the passed event dispatcher with the buses of this context.
      *
@@ -290,6 +305,25 @@ protected void registerEventDispatcher(EventDispatcher dispatcher) {
         }
     }
 
+    protected void unregisterEventDispatcher(EventDispatcher dispatcher) {
+        checkNotNull(dispatcher);
+        Security.allowOnlyFrameworkServer();
+        unregisterIfAware(dispatcher);
+        if (dispatcher.dispatchesEvents()) {
+            var eventBus = eventBus();
+            eventBus.unregister(dispatcher);
+            var systemReadSide = systemClient().readSide();
+            systemReadSide.unregister(dispatcher);
+        }
+        if (dispatcher.dispatchesExternalEvents()) {
+            broker.unregister(dispatcher);
+        }
+        if (dispatcher instanceof CommandDispatcherDelegate) {
+            var commandDispatcher = (CommandDispatcherDelegate) dispatcher;
+            unregisterCommandDispatcher(commandDispatcher);
+        }
+    }
+
     /**
      * Registers the passed delegate of an {@link EventDispatcher} with the buses of this context.
      *
@@ -314,6 +348,19 @@ private void registerIfAware(Object contextPart) {
         }
     }
 
+    /**
+     * If the given {@code contextPart} is {@link ContextAware},
+     * {@linkplain ContextAware#unregister() unregisters} it from this context.
+     */
+    private static void unregisterIfAware(Object contextPart) {
+        if (contextPart instanceof ContextAware) {
+            var contextAware = (ContextAware) contextPart;
+            if (contextAware.isRegistered()) {
+                contextAware.unregister();
+            }
+        }
+    }
+
     /**
      * Obtains a set of entity type names by their visibility.
      */
@@ -440,7 +487,9 @@ public void close() throws Exception {
         if (isOpen) {
             shutDownRepositories();
         }
-
+        if (hasProbe()) {
+            removeProbe();
+        }
         if (isOpen) {
             logger().atDebug().log(() -> format("%s", closed(nameForLogging())));
         }
@@ -503,6 +552,39 @@ public int compareTo(BoundedContext another) {
         return name().value().compareTo(another.name().value());
     }
 
+    public final void install(Probe probe) {
+        checkNotNull(probe);
+        checkState(this.probe == null,
+                   "Probe is already installed (`%s`). Please remove previous probe first.", probe);
+        probe.registerWith(this);
+        commandBus.add(probe.commandListener());
+        eventBus.add(probe.eventListener());
+        probe.eventDispatchers()
+             .forEach(this::registerEventDispatcher);
+
+        this.probe = probe;
+    }
+
+    /**
+     * Removes the currently installed probe, unregistering it with this context.
+     *
+     * @throws IllegalStateException
+     *          if no probe was installed before
+     */
+    public final void removeProbe() {
+        checkState(probe != null, "Probe is not installed.");
+        commandBus.remove(probe.commandListener());
+        eventBus.remove(probe.eventListener());
+        probe.eventDispatchers()
+             .forEach(this::unregisterEventDispatcher);
+        probe.unregister();
+        probe = null;
+    }
+
+    public final boolean hasProbe() {
+        return probe != null;
+    }
+
     /**
      * Returns {@code true} if another bounded context has the same name as this one,
      * {@code false} otherwise.
@@ -524,13 +606,19 @@ public int hashCode() {
         return name().hashCode();
     }
 
+    public interface Probe extends ContextAware {
+        Listener<CommandEnvelope> commandListener();
+        Listener<EventEnvelope> eventListener();
+        Set<EventDispatcher> eventDispatchers();
+    }
+
     /**
      * Provides access to features of {@link BoundedContext} used internally by the framework.
      */
     @Internal
     public final class InternalAccess {
 
-        /** Prevents instantiation from outside. */
+        /** Prevents instantiation from the outside. */
         private InternalAccess() {
         }
 
@@ -574,7 +662,7 @@ public InternalAccess registerEventDispatcher(EventDispatcher dispatcher) {
          * Obtains repositories of the context.
          *
          * @throws IllegalStateException
-         *         if there is not repository entities of which have the passed state
+         *         if there are no repository entities of which have the passed state
          */
         public Repository<?, ?> getRepository(Class<? extends EntityState<?>> stateClass) {
             return guard.get(stateClass);
@@ -591,7 +679,7 @@ public InternalAccess registerEventDispatcher(EventDispatcher dispatcher) {
          * the requested entity is {@linkplain Visibility#NONE not visible}.
          *
          * @param stateCls
-         *         the class of the state of the entity managed by the resulting repository
+         *         the class of the entity state managed by the resulting repository
          * @return the requested repository or {@link Optional#empty()} if the repository manages
          *         a {@linkplain Visibility#NONE non-visible} entity
          * @throws IllegalStateException
diff --git a/server/src/main/java/io/spine/server/ContextAware.java b/server/src/main/java/io/spine/server/ContextAware.java
index fb915b46f71..bb20a77a1eb 100644
--- a/server/src/main/java/io/spine/server/ContextAware.java
+++ b/server/src/main/java/io/spine/server/ContextAware.java
@@ -28,6 +28,8 @@
 
 import io.spine.annotation.Internal;
 
+import javax.annotation.OverridingMethodsMustInvokeSuper;
+
 import static com.google.common.base.Preconditions.checkState;
 
 /**
@@ -53,6 +55,18 @@ public interface ContextAware {
      */
     boolean isRegistered();
 
+    /**
+     * Unregisters this instance from the Bounded Context with which this instance
+     * was {@linkplain #registerWith(BoundedContext) registered before}.
+     *
+     * <p>The default implementation checks if this instance is registered and does nothing else.
+     * Override this method to perform additional actions, making sure to call the super method.
+     */
+    @OverridingMethodsMustInvokeSuper
+    default void unregister() {
+        checkRegistered();
+    }
+
     /**
      * Verifies that this instance is already registered.
      *
@@ -68,6 +82,6 @@ default void checkRegistered() {
      * <p>Throws an {@code IllegalStateException} if already registered.
      */
     default void checkNotRegistered() {
-        checkState(!isRegistered(), "%s is already registered.", this);
+        checkState(!isRegistered(), "`%s` is already registered.", this);
     }
 }
diff --git a/server/src/main/java/io/spine/server/ServerEnvironment.java b/server/src/main/java/io/spine/server/ServerEnvironment.java
index d8c47f9498a..3897bff68d3 100644
--- a/server/src/main/java/io/spine/server/ServerEnvironment.java
+++ b/server/src/main/java/io/spine/server/ServerEnvironment.java
@@ -343,7 +343,7 @@ public static TypeConfigurator when(Class<? extends EnvironmentType<?>> type) {
     }
 
     /**
-     * Allows to configure values used by the {@code ServerEnvironment} for the given type.
+     * Allows configuring values used by the {@code ServerEnvironment} for the given type.
      */
     public static class TypeConfigurator {
 
diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 736b8c04134..7b21b549c4a 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -93,7 +93,8 @@ protected Bus(BusBuilder<?, T, E, C, D> builder) {
      *         exposed} by the dispatcher is empty
      */
     public void register(D dispatcher) {
-        registry().register(checkNotNull(dispatcher));
+        checkNotNull(dispatcher);
+        registry().register(dispatcher);
     }
 
     /**
@@ -102,14 +103,29 @@ public void register(D dispatcher) {
      * @param dispatcher the dispatcher to unregister
      */
     public void unregister(D dispatcher) {
-        registry().unregister(checkNotNull(dispatcher));
+        checkNotNull(dispatcher);
+        registry().unregister(dispatcher);
+    }
+
+    public void unregister(DispatcherDelegate<C, E> delegate) {
+        checkNotNull(delegate);
+    }
+
+    public void add(Listener<E> listener) {
+        checkNotNull(listener);
+        listeners.add(listener);
+    }
+
+    public void remove(Listener<E> listener) {
+        checkNotNull(listener);
+        listeners.remove(listener);
     }
 
     /**
      * Posts the message to the bus.
      *
      * @param message  the message to post
-     * @param observer the observer to receive outcome of the operation
+     * @param observer the observer to receive an outcome of the operation
      * @see #post(Iterable, StreamObserver) for posing multiple messages at once
      */
     public final void post(T message, StreamObserver<Ack> observer) {
@@ -132,18 +148,18 @@ public final void post(T message, StreamObserver<Ack> observer) {
      * {@link io.spine.base.Error Error} status is passed in {@code Ack} instance.
      *
      * <p>Depending on the underlying {@link MessageDispatcher}, a message which causes a business
-     * {@linkplain io.spine.base.RejectionThrowable rejection} may result either a rejection status or
-     * an {@link io.spine.core.Status.StatusCase#OK OK} status {@link Ack} instance.
+     * {@linkplain io.spine.base.RejectionThrowable rejection} may result either a rejection
+     * status or an {@link io.spine.core.Status.StatusCase#OK OK} status {@link Ack} instance.
      * The rejection status may only pop up if the {@link MessageDispatcher} processes the message
      * sequentially and throws the rejection (wrapped in a
-     * the {@linkplain io.spine.base.RejectionThrowable RejectionThrowables}) instead of handling them.
-     * Otherwise, the {@code OK} status should be expected.
+     * the {@linkplain io.spine.base.RejectionThrowable RejectionThrowables}) instead of
+     * handling them. Otherwise, the {@code OK} status should be expected.
      *
      * <p>Note that {@linkplain StreamObserver#onError StreamObserver.onError()} is never called
      * for the passed observer, since errors are propagated as statuses of {@code Ack} response.
      *
      * @param messages the messages to post
-     * @param observer the observer to receive outcome of the operation
+     * @param observer the observer to receive the outcome of the operation
      */
     public final void post(Iterable<T> messages, StreamObserver<Ack> observer) {
         checkNotNull(messages);
diff --git a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
new file mode 100644
index 00000000000..ed21cdd714b
--- /dev/null
+++ b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.server.bus;
+
+import io.spine.annotation.Internal;
+import io.spine.server.type.MessageEnvelope;
+import io.spine.type.MessageClass;
+
+@Internal
+public interface DelegatingDispatcher<C extends MessageClass<?>,
+                                      E extends MessageEnvelope<?, ?, ?>>
+        extends MessageDispatcher<C, E> {
+
+    /**
+     * Obtains the dispatcher to which the messages should be delegated.
+     */
+    DispatcherDelegate<C, E> delegate();
+}
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
new file mode 100644
index 00000000000..17fd40fe0f2
--- /dev/null
+++ b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.server.bus;
+
+import io.spine.server.type.MessageEnvelope;
+import io.spine.type.MessageClass;
+
+public interface DispatcherDelegate<C extends MessageClass<?>,
+                                    E extends MessageEnvelope<?, ?, ?>> {
+
+}
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java b/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
index a3024e6f0d3..42a7f2fa3dd 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
@@ -86,6 +86,18 @@ public void unregister(D dispatcher) {
         }
     }
 
+    public void unregister(DispatcherDelegate<C, E> delegate) {
+        checkNotNull(delegate);
+        @SuppressWarnings("unchecked") // Checked with `instanceof`.
+        var delegatingDispatcher = dispatchers.values().stream()
+                .filter(d -> d instanceof DelegatingDispatcher)
+                .map(d -> (DelegatingDispatcher<C, E>) d)
+                .filter(d -> d.delegate().equals(delegate))
+                .map(d -> (D) d)
+                .findFirst();
+        delegatingDispatcher.ifPresent(this::unregister);
+    }
+
     /**
      * Unregisters all dispatchers.
      */
diff --git a/server/src/main/java/io/spine/server/bus/Listeners.java b/server/src/main/java/io/spine/server/bus/Listeners.java
index 3183112763e..e7325a34b87 100644
--- a/server/src/main/java/io/spine/server/bus/Listeners.java
+++ b/server/src/main/java/io/spine/server/bus/Listeners.java
@@ -27,12 +27,14 @@
 package io.spine.server.bus;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.ImmutableSet;
 import io.spine.server.type.SignalEnvelope;
 
+import java.util.HashSet;
+import java.util.Set;
 import java.util.function.Consumer;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Collections.synchronizedSet;
 
 /**
  * Manages consumption of a message posted to the bus by its listeners.
@@ -41,11 +43,21 @@
  */
 final class Listeners<E extends SignalEnvelope<?, ?, ?>> implements Consumer<E> {
 
-    private final ImmutableSet<Listener<E>> listeners;
+    private final Set<Listener<E>> listeners = synchronizedSet(new HashSet<>());
 
     Listeners(BusBuilder<?, ?, E, ?, ?> builder) {
         checkNotNull(builder);
-        this.listeners = ImmutableSet.copyOf(builder.listeners());
+        listeners.addAll(builder.listeners());
+    }
+
+    void add(Listener<E> listener) {
+        checkNotNull(listener);
+        listeners.add(listener);
+    }
+
+    void remove(Listener<E> listener) {
+        checkNotNull(listener);
+        listeners.remove(listener);
     }
 
     @Override
diff --git a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
index f256d888363..2fb22dd56c7 100644
--- a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
@@ -27,6 +27,7 @@
 
 import com.google.common.collect.ImmutableSet;
 import io.spine.annotation.Internal;
+import io.spine.server.bus.DispatcherDelegate;
 import io.spine.server.dispatch.DispatchOutcome;
 import io.spine.server.type.CommandClass;
 import io.spine.server.type.CommandEnvelope;
@@ -61,7 +62,8 @@
  * @see DelegatingCommandDispatcher
  */
 @Internal
-public interface CommandDispatcherDelegate {
+public interface CommandDispatcherDelegate
+        extends DispatcherDelegate<CommandClass, CommandEnvelope> {
 
     /**
      * Obtains the classes of dispatched commands.
@@ -69,7 +71,7 @@ public interface CommandDispatcherDelegate {
     ImmutableSet<CommandClass> commandClasses();
 
     /**
-     * Dispatches the command  and returns the outcome of the dispatching.
+     * Dispatches the command and returns the outcome of the dispatching.
      */
     DispatchOutcome dispatchCommand(CommandEnvelope envelope);
 
diff --git a/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java b/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
index e7187312dcb..50e1829ffe5 100644
--- a/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
+++ b/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
@@ -28,6 +28,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import io.spine.annotation.Internal;
+import io.spine.server.bus.DelegatingDispatcher;
 import io.spine.server.dispatch.DispatchOutcome;
 import io.spine.server.type.CommandClass;
 import io.spine.server.type.CommandEnvelope;
@@ -39,7 +40,9 @@
  * @see CommandDispatcherDelegate
  */
 @Internal
-public class DelegatingCommandDispatcher implements CommandDispatcher {
+public class DelegatingCommandDispatcher
+        implements CommandDispatcher,
+                   DelegatingDispatcher<CommandClass, CommandEnvelope> {
 
     /**
      * A target delegate.
@@ -70,6 +73,11 @@ public final DispatchOutcome dispatch(CommandEnvelope envelope) {
         return delegate.dispatchCommand(envelope);
     }
 
+    @Override
+    public CommandDispatcherDelegate delegate() {
+        return delegate;
+    }
+
     /**
      * Returns the string representation of this dispatcher.
      *
diff --git a/server/src/main/java/io/spine/server/event/DelegatingEventDispatcher.java b/server/src/main/java/io/spine/server/event/DelegatingEventDispatcher.java
index 8a8be712b7c..cd3729869bc 100644
--- a/server/src/main/java/io/spine/server/event/DelegatingEventDispatcher.java
+++ b/server/src/main/java/io/spine/server/event/DelegatingEventDispatcher.java
@@ -29,6 +29,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableSet;
 import io.spine.annotation.Internal;
+import io.spine.server.bus.DelegatingDispatcher;
 import io.spine.server.dispatch.DispatchOutcome;
 import io.spine.server.type.EventClass;
 import io.spine.server.type.EventEnvelope;
@@ -42,7 +43,9 @@
  * @see EventDispatcherDelegate
  */
 @Internal
-public final class DelegatingEventDispatcher implements EventDispatcher {
+public final class DelegatingEventDispatcher
+        implements EventDispatcher,
+                   DelegatingDispatcher<EventClass, EventEnvelope> {
 
     /**
      * A target delegate.
@@ -90,6 +93,11 @@ public boolean canDispatch(EventEnvelope envelope) {
         return delegate.canDispatchEvent(envelope);
     }
 
+    @Override
+    public EventDispatcherDelegate delegate() {
+        return delegate;
+    }
+
     /**
      * Returns the string representation of this dispatcher.
      *
diff --git a/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java b/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
index 59ea5b1419c..ad6b8fcacae 100644
--- a/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
@@ -28,6 +28,7 @@
 
 import com.google.common.collect.ImmutableSet;
 import io.spine.annotation.Internal;
+import io.spine.server.bus.DispatcherDelegate;
 import io.spine.server.dispatch.DispatchOutcome;
 import io.spine.server.type.EventClass;
 import io.spine.server.type.EventEnvelope;
@@ -44,7 +45,7 @@
  * @see DelegatingEventDispatcher
  */
 @Internal
-public interface EventDispatcherDelegate {
+public interface EventDispatcherDelegate extends DispatcherDelegate<EventClass, EventEnvelope> {
 
     /**
      * Obtains all event classes dispatched by this delegate.
@@ -96,7 +97,7 @@ default boolean dispatchesExternalEvents() {
     /**
      * Checks if this dispatcher can dispatch the given event.
      *
-     * <p>By default, all events are permitted. Implementations may change this behaviour to reject
+     * <p>By default, all events are permitted. Implementations may change this behavior to reject
      * certain events as early as possible.
      *
      * @param envelope
diff --git a/server/src/main/java/io/spine/system/server/SystemContext.java b/server/src/main/java/io/spine/system/server/SystemContext.java
index 712177d1f29..bb444bf3b14 100644
--- a/server/src/main/java/io/spine/system/server/SystemContext.java
+++ b/server/src/main/java/io/spine/system/server/SystemContext.java
@@ -108,8 +108,8 @@ public SystemClient createClient() {
     /**
      * {@inheritDoc}
      *
-     * <p>Since a system bounded context does not have an associated system bounded context, returns
-     * a {@link NoOpSystemWriteSide} instance.
+     * <p>Since a system-bounded context does not have an associated system bounded context,
+     * the method returns a {@link NoOpSystemWriteSide} instance.
      */
     @Override
     public NoOpSystemClient systemClient() {
diff --git a/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java b/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
index 59041a4efbe..ba0187ceca5 100644
--- a/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
@@ -84,8 +84,7 @@
 @SuppressWarnings("AbstractClassWithoutAbstractMethods") // designed for the various storage impls.
 public abstract class AggregateHistoryTruncationTest {
 
-    private static final SequenceId ID = SequenceId
-            .newBuilder()
+    private static final SequenceId ID = SequenceId.newBuilder()
             .setValue(newUuid())
             .build();
 
@@ -101,49 +100,50 @@ void restoreAggregateState() {
                     BoundedContextBuilder.assumingTests()
                                          .add(repo)
             );
-
-            // Set the starting numbers.
-            var setStartingNumbers = SetStartingNumbers.newBuilder()
-                    .setId(ID)
-                    .setNumberOne(0)
-                    .setNumberTwo(1)
-                    .build();
-            context.receivesCommand(setStartingNumbers)
-                   .assertEvents()
-                   .withType(StartingNumbersSet.class)
-                   .hasSize(1);
-            // Send a lot of `MoveSequence` events, so several snapshots are created.
-            var moveSequence = MoveSequence.newBuilder()
-                    .setId(ID)
-                    .build();
-            var snapshotTrigger = repo.snapshotTrigger();
-            for (var i = 0; i < snapshotTrigger * 5 + 1; i++) {
+            try (context) {
+                // Set the starting numbers.
+                var setStartingNumbers = SetStartingNumbers.newBuilder()
+                        .setId(ID)
+                        .setNumberOne(0)
+                        .setNumberTwo(1)
+                        .build();
+                context.receivesCommand(setStartingNumbers)
+                       .assertEvents()
+                       .withType(StartingNumbersSet.class)
+                       .hasSize(1);
+                // Send a lot of `MoveSequence` events, so several snapshots are created.
+                var moveSequence = MoveSequence.newBuilder()
+                        .setId(ID)
+                        .build();
+                var snapshotTrigger = repo.snapshotTrigger();
+                for (var i = 0; i < snapshotTrigger * 5 + 1; i++) {
+                    context.receivesCommand(moveSequence);
+                }
+
+                // Compare against the numbers calculated by hand.
+                var expectedNumberOne = 121393;
+                var expectedNumberTwo = 196418;
+                assertThat(lastNumberOne())
+                        .isEqualTo(expectedNumberOne);
+                assertThat(lastNumberTwo())
+                        .isEqualTo(expectedNumberTwo);
+
+                // Truncate the storage.
+                var storage = repo.aggregateStorage();
+                var countBeforeTruncate = recordCount(storage);
+                assertThat(countBeforeTruncate)
+                        .isGreaterThan(snapshotTrigger);
+                storage.truncateOlderThan(0);
+                var countAfterTruncate = recordCount(storage);
+                assertThat(countAfterTruncate)
+                        .isAtMost(snapshotTrigger);
+
+                // Run one more command and check the result.
+                var expectedNext = lastNumberOne() + lastNumberTwo();
                 context.receivesCommand(moveSequence);
+                assertThat(lastNumberTwo())
+                        .isEqualTo(expectedNext);
             }
-
-            // Compare against the numbers calculated by hand.
-            var expectedNumberOne = 121393;
-            var expectedNumberTwo = 196418;
-            assertThat(lastNumberOne())
-                    .isEqualTo(expectedNumberOne);
-            assertThat(lastNumberTwo())
-                    .isEqualTo(expectedNumberTwo);
-
-            // Truncate the storage.
-            var storage = repo.aggregateStorage();
-            var countBeforeTruncate = recordCount(storage);
-            assertThat(countBeforeTruncate)
-                    .isGreaterThan(snapshotTrigger);
-            storage.truncateOlderThan(0);
-            var countAfterTruncate = recordCount(storage);
-            assertThat(countAfterTruncate)
-                    .isAtMost(snapshotTrigger);
-
-            // Run one more command and check the result.
-            var expectedNext = lastNumberOne() + lastNumberTwo();
-            context.receivesCommand(moveSequence);
-            assertThat(lastNumberTwo())
-                    .isEqualTo(expectedNext);
         }
 
         private int recordCount(AggregateStorage<SequenceId, Sequence> storage) {
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 0a6ad44f652..0da9b3ca994 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -56,6 +56,9 @@
 import io.spine.testing.server.CommandSubject;
 import io.spine.testing.server.EventSubject;
 import io.spine.testing.server.entity.EntitySubject;
+import io.spine.testing.server.blackbox.probe.CommandCollector;
+import io.spine.testing.server.blackbox.probe.EventCollector;
+import io.spine.testing.server.blackbox.probe.Probe;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
@@ -152,10 +155,10 @@ public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder) {
     BlackBox(BoundedContextBuilder builder) {
         super();
         this.probe = new Probe();
-        probe.installIn(builder);
         var created = this;
         builder.setOnBuild(context -> {
             created.clientFactory = new ClientFactory(context);
+            context.install(probe);
             created.context = context;
         });
         this.actor = defaultActor();
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
index 2298fc3f114..1cb02238ac4 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
@@ -34,6 +34,8 @@
 import io.spine.server.BoundedContextBuilder;
 import io.spine.server.tenant.TenantAwareRunner;
 import io.spine.testing.client.TestActorRequestFactory;
+import io.spine.testing.server.blackbox.probe.CommandCollector;
+import io.spine.testing.server.blackbox.probe.EventCollector;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
index 6ed954ed7c3..73112183c3a 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
@@ -33,7 +33,8 @@
 import io.spine.core.TenantId;
 import io.spine.server.BoundedContextBuilder;
 import io.spine.testing.client.TestActorRequestFactory;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import io.spine.testing.server.blackbox.probe.CommandCollector;
+import io.spine.testing.server.blackbox.probe.EventCollector;
 
 import static com.google.protobuf.TextFormat.shortDebugString;
 import static io.spine.util.Exceptions.newIllegalStateException;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/package-info.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/package-info.java
index 362c89297e1..aca90f6206d 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/package-info.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/package-info.java
@@ -32,7 +32,7 @@
  * <p>One such black box example is for {@link io.spine.testing.server.blackbox.BlackBox
  * Bounded Context testing}. It allows sending Commands and Events to the 
  * {@link io.spine.server.BoundedContext Bounded Context} and then verifying their effect 
- * inside of the Bounded Context.
+ * inside the Bounded Context.
  * 
  * @see io.spine.testing.server.blackbox.BlackBox
  */
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/CommandCollector.java
similarity index 93%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/CommandCollector.java
index 3a91478e4e7..0f515289034 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/CommandCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/CommandCollector.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import io.spine.core.Command;
 import io.spine.core.CommandId;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLog.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLog.java
similarity index 97%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLog.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLog.java
index 43a2f57db88..999e666346e 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLog.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLog.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import io.spine.base.Identifier;
 import io.spine.core.Subscribe;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLogging.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
similarity index 98%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLogging.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
index bbe7c6f328a..9e6795694b6 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/DiagnosticLogging.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import com.google.errorprone.annotations.FormatMethod;
 import com.google.errorprone.annotations.FormatString;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/EventCollector.java
similarity index 93%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/EventCollector.java
index 92872356b6e..26fd3f3a526 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/EventCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/EventCollector.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import io.spine.core.Event;
 import io.spine.core.EventId;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
similarity index 98%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
index d62bba67018..3fcd836feb6 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/FailedHandlerGuard.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableSet;
@@ -34,8 +34,8 @@
 import io.spine.server.type.EventEnvelope;
 import io.spine.system.server.HandlerFailedUnexpectedly;
 
-import static io.spine.type.Json.toJson;
 import static io.spine.server.dispatch.DispatchOutcomes.successfulOutcome;
+import static io.spine.type.Json.toJson;
 import static java.lang.String.format;
 import static java.lang.System.lineSeparator;
 import static org.junit.jupiter.api.Assertions.fail;
@@ -97,7 +97,7 @@ void on(HandlerFailedUnexpectedly event) {
     /**
      * Asks the guard to tolerate exceptions.
      */
-    void tolerateFailures() {
+    public void tolerateFailures() {
         tolerance = HandlerFailureTolerance.LOG;
     }
 
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/HandlerFailureTolerance.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/HandlerFailureTolerance.java
similarity index 91%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/HandlerFailureTolerance.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/HandlerFailureTolerance.java
index af6b3b6fa7d..c2dd85d59ad 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/HandlerFailureTolerance.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/HandlerFailureTolerance.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,9 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
+
+import io.spine.testing.server.blackbox.BlackBox;
 
 /**
  * Configures the behavior of the {@link BlackBox} on handling runtime exceptions
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
similarity index 97%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
index d5df7c42463..fac7a68a197 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MessageCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.truth.extensions.proto.ProtoTruth;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
similarity index 62%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
index b2750bda458..89c02625bd7 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/Probe.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
@@ -24,11 +24,24 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
+import com.google.common.collect.ImmutableSet;
+import io.spine.server.BoundedContext;
 import io.spine.server.BoundedContextBuilder;
+import io.spine.server.bus.Listener;
+import io.spine.server.event.EventDispatcher;
+import io.spine.server.type.CommandEnvelope;
+import io.spine.server.type.EventEnvelope;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
-public class Probe {
+import java.util.Set;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+public class Probe implements BoundedContext.Probe {
+
+    private @Nullable BoundedContext context;
 
     /**
      * Collects all commands, including posted to the context during its setup or
@@ -47,12 +60,23 @@ public class Probe {
      */
     private final FailedHandlerGuard failedHandlerGuard;
 
-    Probe() {
+    public Probe() {
         this.commands = new CommandCollector();
         this.events = new EventCollector();
         this.failedHandlerGuard = new FailedHandlerGuard();
     }
 
+    @Override
+    public void registerWith(BoundedContext context) {
+        checkNotRegistered();
+        this.context = checkNotNull(context);
+    }
+
+    @Override
+    public boolean isRegistered() {
+        return context != null;
+    }
+
     public CommandCollector commands() {
         return commands;
     }
@@ -65,12 +89,25 @@ public FailedHandlerGuard failedHandlerGuard() {
         return failedHandlerGuard;
     }
 
-    public void installIn(BoundedContextBuilder builder) {
-        builder.addCommandListener(commands())
-               .addEventListener(events())
-               .addEventDispatcher(failedHandlerGuard())
-               .addEventDispatcher(new UnsupportedCommandGuard(builder.name()
-                                                                      .getValue()))
-               .addEventDispatcher(DiagnosticLog.instance());
+    @Override
+    public Listener<CommandEnvelope> commandListener() {
+        return commands();
+    }
+
+    @Override
+    public Listener<EventEnvelope> eventListener() {
+        return events();
+    }
+
+    @Override
+    public Set<EventDispatcher> eventDispatchers() {
+        checkRegistered();
+        assert(context != null);
+        var commandGuard = new UnsupportedCommandGuard(context.name().value());
+        return ImmutableSet.of(
+                failedHandlerGuard(),
+                commandGuard,
+                DiagnosticLog.instance()
+        );
     }
 }
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/UnsupportedCommandGuard.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuard.java
similarity index 97%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/UnsupportedCommandGuard.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuard.java
index 99bc8efbd0f..8f2a917b942 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/UnsupportedCommandGuard.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuard.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableSet;
@@ -35,6 +35,7 @@
 import io.spine.server.type.EventClass;
 import io.spine.server.type.EventEnvelope;
 import io.spine.system.server.event.CommandErrored;
+import io.spine.testing.server.blackbox.BlackBox;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import static io.spine.core.CommandValidationError.UNSUPPORTED_COMMAND_VALUE;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
new file mode 100644
index 00000000000..0bf3d522413
--- /dev/null
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * This package contains diagnostic utilities for
+ * {@link io.spine.server.BoundedContext io.spine.server.BoundedContext}.
+ */
+@CheckReturnValue
+@ParametersAreNonnullByDefault
+package io.spine.testing.server.blackbox.probe;
+
+import com.google.errorprone.annotations.CheckReturnValue;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/UnsupportedCommandGuardTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/UnsupportedCommandGuardTest.java
deleted file mode 100644
index 89a340b733a..00000000000
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/UnsupportedCommandGuardTest.java
+++ /dev/null
@@ -1,75 +0,0 @@
-/*
- * Copyright 2022, TeamDev. All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Redistribution and use in source and/or binary forms, with or without
- * modification, must retain the above copyright notice and the following
- * disclaimer.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-package io.spine.testing.server.blackbox;
-
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.DisplayName;
-import org.junit.jupiter.api.Test;
-
-import static com.google.common.truth.Truth.assertThat;
-import static io.spine.testing.server.blackbox.given.GivenCommandError.duplicationError;
-import static io.spine.testing.server.blackbox.given.GivenCommandError.nonValidationError;
-import static io.spine.testing.server.blackbox.given.GivenCommandError.unsupportedError;
-
-@DisplayName("`UnsupportedCommandGuard` should")
-class UnsupportedCommandGuardTest {
-
-    private UnsupportedCommandGuard guard;
-
-    @BeforeEach
-    void initGuard() {
-        guard = new UnsupportedCommandGuard(getClass().getName());
-    }
-
-    @Test
-    @DisplayName("check and remember the unsupported command error")
-    void checkAndRememberUnsupported() {
-        var commandType = "SomeCommand";
-        var result = guard.checkAndRemember(unsupportedError(commandType));
-
-        assertThat(result).isTrue();
-        assertThat(guard.commandType()).isEqualTo(commandType);
-    }
-
-    @Test
-    @DisplayName("return `false` and ignore the command validation error with the different code")
-    void ignoreGenericValidationError() {
-        var result = guard.checkAndRemember(duplicationError());
-
-        assertThat(result).isFalse();
-        assertThat(guard.commandType()).isNull();
-    }
-
-    @Test
-    @DisplayName("return `false` and ignore the command error of the different type")
-    void ignoreGenericCommandError() {
-        var result = guard.checkAndRemember(nonValidationError());
-
-        assertThat(result).isFalse();
-        assertThat(guard.commandType()).isNull();
-    }
-}
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/given/BbProjectFailerProcess.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/given/BbProjectFailerProcess.java
index fa1f5d47328..2d085e6325c 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/given/BbProjectFailerProcess.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/given/BbProjectFailerProcess.java
@@ -34,10 +34,11 @@
 import io.spine.testing.server.blackbox.BbProjectId;
 import io.spine.testing.server.blackbox.command.BbFailProject;
 import io.spine.testing.server.blackbox.event.BbProjectFailed;
+import io.spine.testing.server.blackbox.probe.FailedHandlerGuard;
 
 /**
  * Test environment for testing
- * {@link io.spine.testing.server.blackbox.FailedHandlerGuard FailedHandlerGuard} integration.
+ * {@link FailedHandlerGuard FailedHandlerGuard} integration.
  */
 public final class BbProjectFailerProcess
         extends ProcessManager<BbProjectId, BbProjectFailer, BbProjectFailer.Builder> {
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLogTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLogTest.java
similarity index 98%
rename from testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLogTest.java
rename to testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLogTest.java
index aafb01f9a2f..f4dcb3f3924 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLogTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLogTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import io.spine.base.Identifier;
 import io.spine.core.CommandId;
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLoggingTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLoggingTest.java
similarity index 95%
rename from testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLoggingTest.java
rename to testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLoggingTest.java
index 2611f1c0460..75b95e8c0e8 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/DiagnosticLoggingTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/DiagnosticLoggingTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,10 +24,11 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import com.google.protobuf.Empty;
 import io.spine.core.MessageId;
+import io.spine.testing.server.blackbox.probe.DiagnosticLogging;
 import io.spine.type.TypeUrl;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/FailedHandlerGuardTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuardTest.java
similarity index 96%
rename from testutil-server/src/test/java/io/spine/testing/server/blackbox/FailedHandlerGuardTest.java
rename to testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuardTest.java
index 2c669f8ceaf..8a9480160fa 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/FailedHandlerGuardTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuardTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -24,7 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.testing.server.blackbox;
+package io.spine.testing.server.blackbox.probe;
 
 import io.spine.system.server.HandlerFailedUnexpectedly;
 import org.junit.jupiter.api.BeforeEach;
diff --git a/testutil-server/src/test/kotlin/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuardSpec.kt b/testutil-server/src/test/kotlin/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuardSpec.kt
new file mode 100644
index 00000000000..cbf8a55f22e
--- /dev/null
+++ b/testutil-server/src/test/kotlin/io/spine/testing/server/blackbox/probe/UnsupportedCommandGuardSpec.kt
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package io.spine.testing.server.blackbox.probe
+
+import io.kotest.matchers.shouldBe
+import io.spine.testing.server.blackbox.given.GivenCommandError.duplicationError
+import io.spine.testing.server.blackbox.given.GivenCommandError.nonValidationError
+import io.spine.testing.server.blackbox.given.GivenCommandError.unsupportedError
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+
+@DisplayName("`UnsupportedCommandGuard` should")
+internal class UnsupportedCommandGuardSpec {
+
+    private lateinit var guard: UnsupportedCommandGuard
+
+    @BeforeEach
+    fun initGuard() {
+        guard = UnsupportedCommandGuard(javaClass.name)
+    }
+
+    @Test
+    fun `check and remember the unsupported command error`() {
+        val commandType = "SomeCommand"
+        val result = guard.checkAndRemember(unsupportedError(commandType))
+
+        result shouldBe true
+        guard.commandType() shouldBe commandType
+    }
+
+    @Test
+    fun `return 'false' and ignore the command validation error with the different code`() {
+        val result = guard.checkAndRemember(duplicationError())
+
+        result shouldBe false
+        guard.commandType() shouldBe null
+    }
+
+    @Test
+    fun `return 'false' and ignore the command error of the different type`() {
+        val result = guard.checkAndRemember(nonValidationError())
+
+        result shouldBe false
+        guard.commandType() shouldBe null
+    }
+}

From 0cca1d4687fc475bb2cef40ac45e1f329a1fab49 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Mon, 30 Oct 2023 18:46:44 +0000
Subject: [PATCH 07/32] Pass `BoundedContext` to `BlackBox`

... instead of `BoundedContextBuilder`.
---
 .../java/io/spine/server/BoundedContext.java  | 10 ++---
 .../spine/server/BoundedContextBuilder.java   | 25 ++++-------
 .../testing/server/blackbox/BlackBox.java     | 42 ++++++-------------
 .../testing/server/blackbox/MtBlackBox.java   |  6 +--
 .../testing/server/blackbox/StBlackBox.java   |  6 +--
 5 files changed, 30 insertions(+), 59 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index f2bc047ff60..f598b9c89a1 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -46,13 +46,10 @@
 import io.spine.server.event.EventBus;
 import io.spine.server.event.EventDispatcher;
 import io.spine.server.event.EventDispatcherDelegate;
-import io.spine.server.event.store.DefaultEventStore;
 import io.spine.server.integration.IntegrationBroker;
 import io.spine.server.security.Security;
 import io.spine.server.stand.Stand;
-import io.spine.server.storage.StorageFactory;
 import io.spine.server.tenant.TenantIndex;
-import io.spine.server.trace.TracerFactory;
 import io.spine.server.type.CommandEnvelope;
 import io.spine.server.type.EventEnvelope;
 import io.spine.system.server.SystemClient;
@@ -457,15 +454,15 @@ public boolean isMultitenant() {
      *
      * <p>This method performs the following:
      * <ol>
-     *     <li>Closes associated {@link StorageFactory}.
+     *     <li>Invokes {@link BoundedContextBuilder#getOnBeforeClose onBeforeClose} if it was
+     *      configured when the context was {@linkplain BoundedContextBuilder built}.
      *     <li>Closes {@link CommandBus}.
      *     <li>Closes {@link EventBus}.
      *     <li>Closes {@link IntegrationBroker}.
-     *     <li>Closes {@link DefaultEventStore EventStore}.
      *     <li>Closes {@link Stand}.
      *     <li>Closes {@link ImportBus}.
-     *     <li>Closes {@link TracerFactory} if it is present.
      *     <li>Closes all registered {@linkplain Repository repositories}.
+     *     <li>Removes a {@link Probe}, if it was {@linkplain #install(Probe) installed}.
      * </ol>
      *
      * @throws Exception
@@ -561,7 +558,6 @@ public final void install(Probe probe) {
         eventBus.add(probe.eventListener());
         probe.eventDispatchers()
              .forEach(this::registerEventDispatcher);
-
         this.probe = probe;
     }
 
diff --git a/server/src/main/java/io/spine/server/BoundedContextBuilder.java b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
index d3c03d4cd2d..c4b0c76e669 100644
--- a/server/src/main/java/io/spine/server/BoundedContextBuilder.java
+++ b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
@@ -104,8 +104,6 @@ public final class BoundedContextBuilder implements WithLogging {
     /** Repositories to be registered with the Bounded Context being built after its creation. */
     private final Collection<Repository<?, ?>> repositories = new ArrayList<>();
 
-    private @Nullable Consumer<BoundedContextBuilder> onBeforeBuild = null;
-    private @Nullable Consumer<BoundedContext> onBuild = null;
     private @Nullable Consumer<BoundedContext> onBeforeClose = null;
 
     /**
@@ -541,9 +539,6 @@ public SystemSettings systemSettings() {
      * @return new {@code BoundedContext}
      */
     public BoundedContext build() {
-        if (onBeforeBuild != null) {
-            onBeforeBuild.accept(this);
-        }
         var system = buildSystem();
         var result = buildDomain(system);
         logger().atDebug()
@@ -554,9 +549,6 @@ public BoundedContext build() {
         ServerEnvironment.instance()
                          .delivery()
                          .registerDispatchersIn(result);
-        if (onBuild != null) {
-            onBuild.accept(result);
-        }
         return result;
     }
 
@@ -567,14 +559,15 @@ EventBus buildEventBus(BoundedContext context) {
         return eventBus.build();
     }
 
-    public void setOnBeforeBuild(Consumer<BoundedContextBuilder> consumer) {
-        this.onBeforeBuild = checkNotNull(consumer);
-    }
-
-    public void setOnBuild(Consumer<BoundedContext> consumer) {
-        this.onBuild = checkNotNull(consumer);
-    }
-
+    /**
+     * Sets the action to be performed before the context is closed.
+     *
+     * <p>The action is performed after the context is closed, but before the
+     * {@linkplain BoundedContext#onClose() context's own action} is performed.
+     *
+     * @param consumer
+     *         the action to perform
+     */
     public void setOnBeforeClose(Consumer<BoundedContext> consumer) {
         this.onBeforeClose = checkNotNull(consumer);
     }
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 0da9b3ca994..356510dec56 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -55,20 +55,18 @@
 import io.spine.testing.client.TestActorRequestFactory;
 import io.spine.testing.server.CommandSubject;
 import io.spine.testing.server.EventSubject;
-import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.blackbox.probe.CommandCollector;
 import io.spine.testing.server.blackbox.probe.EventCollector;
 import io.spine.testing.server.blackbox.probe.Probe;
+import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
-import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
@@ -95,7 +93,7 @@ public abstract class BlackBox implements WithLogging, Closeable {
     /**
      * The context under the test.
      */
-    private @MonotonicNonNull BoundedContext context;
+    private final BoundedContext context;
 
     /**
      * The probe inserted into the context under the test.
@@ -105,7 +103,7 @@ public abstract class BlackBox implements WithLogging, Closeable {
     /**
      * A factory of {@link Client}s which send requests to this context.
      */
-    private @MonotonicNonNull ClientFactory clientFactory;
+    private final ClientFactory clientFactory;
 
     /**
      * Information about the current user and the time-zone.
@@ -132,35 +130,19 @@ public abstract class BlackBox implements WithLogging, Closeable {
      * Creates new instance obtaining configuration parameters from the passed builder.
      */
     public static BlackBox from(BoundedContextBuilder builder) {
-        var supplier = initLazilyFrom(builder);
-        var ignored = builder.build();
-        return supplier.get();
-    }
-
-    /**
-     * Arranged a delayed creation of new {@code Blackbox} obtaining configuration parameters
-     * from the passed builder.
-     */
-    public static Supplier<BlackBox> initLazilyFrom(BoundedContextBuilder builder) {
-        var result = new AtomicReference<BlackBox>();
-        builder.setOnBeforeBuild(configuredBuilder -> {
-            var box = builder.isMultitenant()
-                      ? new MtBlackBox(configuredBuilder)
-                      : new StBlackBox(configuredBuilder);
-            result.set(box);
-        });
-        return result::get;
+        var context = builder.build();
+        var box = builder.isMultitenant()
+                  ? new MtBlackBox(context)
+                  : new StBlackBox(context);
+        return box;
     }
 
-    BlackBox(BoundedContextBuilder builder) {
+    BlackBox(BoundedContext context) {
         super();
+        this.context = context;
         this.probe = new Probe();
-        var created = this;
-        builder.setOnBuild(context -> {
-            created.clientFactory = new ClientFactory(context);
-            context.install(probe);
-            created.context = context;
-        });
+        context.install(probe);
+        this.clientFactory = new ClientFactory(context);
         this.actor = defaultActor();
         this.postedCommands = synchronizedSet(new HashSet<>());
         this.postedEvents = synchronizedSet(new HashSet<>());
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
index 1cb02238ac4..3dd4426d7fd 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/MtBlackBox.java
@@ -31,7 +31,7 @@
 import io.spine.core.Command;
 import io.spine.core.Event;
 import io.spine.core.TenantId;
-import io.spine.server.BoundedContextBuilder;
+import io.spine.server.BoundedContext;
 import io.spine.server.tenant.TenantAwareRunner;
 import io.spine.testing.client.TestActorRequestFactory;
 import io.spine.testing.server.blackbox.probe.CommandCollector;
@@ -54,8 +54,8 @@ final class MtBlackBox extends BlackBox {
     /**
      * Creates a new multi-tenant instance.
      */
-    MtBlackBox(BoundedContextBuilder b) {
-        super(b);
+    MtBlackBox(BoundedContext c) {
+        super(c);
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
index 73112183c3a..219093f2714 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/StBlackBox.java
@@ -31,7 +31,7 @@
 import io.spine.core.Command;
 import io.spine.core.Event;
 import io.spine.core.TenantId;
-import io.spine.server.BoundedContextBuilder;
+import io.spine.server.BoundedContext;
 import io.spine.testing.client.TestActorRequestFactory;
 import io.spine.testing.server.blackbox.probe.CommandCollector;
 import io.spine.testing.server.blackbox.probe.EventCollector;
@@ -44,8 +44,8 @@
  */
 final class StBlackBox extends BlackBox {
 
-    StBlackBox(BoundedContextBuilder b) {
-        super(b);
+    StBlackBox(BoundedContext c) {
+        super(c);
     }
 
     @Override

From 723eb67e339605b45ed4054cfe0dd07aadc39421 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Mon, 30 Oct 2023 19:25:55 +0000
Subject: [PATCH 08/32] Add documentation

---
 .../java/io/spine/server/BoundedContext.java  | 17 ++++++++++
 .../testing/server/blackbox/BlackBox.java     | 10 +++---
 .../blackbox/probe/DiagnosticLogging.java     |  6 ++--
 .../blackbox/probe/FailedHandlerGuard.java    |  4 ++-
 .../blackbox/probe/MessageCollector.java      | 10 +++---
 .../testing/server/blackbox/probe/Probe.java  | 31 +++++++++----------
 .../server/blackbox/probe/package-info.java   |  2 ++
 7 files changed, 51 insertions(+), 29 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index f598b9c89a1..10825c1934d 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -602,9 +602,26 @@ public int hashCode() {
         return name().hashCode();
     }
 
+    /**
+     * A diagnostic probe which can be {@linkplain #install(Probe) installed} into
+     * a Bounded Context to collect information about the commands and events processed by it.
+     */
     public interface Probe extends ContextAware {
+
+        /**
+         * The listener of commands posted processed by the context.
+         */
         Listener<CommandEnvelope> commandListener();
+
+        /**
+         * The listener of events posted processed by the context.
+         */
         Listener<EventEnvelope> eventListener();
+
+        /**
+         * Obtains the event dispatchers exposed by the probe for gathering
+         * additional information about the events.
+         */
         Set<EventDispatcher> eventDispatchers();
     }
 
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 356510dec56..88813aa3487 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -471,8 +471,8 @@ public boolean isOpen() {
     abstract TestActorRequestFactory requestFactory();
 
     /**
-     * Obtains immutable list of commands generated in this Bounded Context in response to posted
-     * messages.
+     * Obtains an immutable list of commands generated in this Bounded Context in response
+     * to posted messages.
      *
      * <p>The returned list does <em>NOT</em> contain commands posted to this Bounded Context
      * during test setup.
@@ -480,7 +480,7 @@ public boolean isOpen() {
     private ImmutableList<Command> commands() {
         var wasNotReceived =
                 ((Predicate<Command>) postedCommands::contains).negate();
-        return select(probe.commands())
+        return select(probe.commandListener())
                 .stream()
                 .filter(wasNotReceived)
                 .collect(toImmutableList());
@@ -511,11 +511,11 @@ private ImmutableList<Event> events() {
     abstract ImmutableList<Event> select(EventCollector collector);
 
     /**
-     * Obtains immutable list of all the events in this Bounded Context.
+     * Obtains an immutable list of all the events in this Bounded Context.
      */
     @VisibleForTesting
     final ImmutableList<Event> allEvents() {
-        return select(probe.events());
+        return select(probe.eventListener());
     }
 
     /**
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
index 9e6795694b6..0b94fe7d3bf 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/DiagnosticLogging.java
@@ -49,7 +49,9 @@ interface DiagnosticLogging extends WithLogging {
      *         the arguments, if any, for the error message
      */
     @FormatMethod
-    default void log(DiagnosticEvent event, @FormatString String errorMessage, Object... formatArgs) {
+    default void log(DiagnosticEvent event,
+                     @FormatString String errorMessage,
+                     Object... formatArgs) {
         var msg = format(errorMessage, formatArgs);
         log(msg, event);
     }
@@ -70,7 +72,7 @@ default void log(String msg, DiagnosticEvent event) {
             errorLogger.log(() -> eventJson);
         } else {
             @SuppressWarnings("UseOfSystemOutOrSystemErr")
-            // Edge case for disabled/misconfigured logging .
+            // Edge case for disabled/misconfigured logging.
             var stderr = System.err;
             stderr.println(msg);
             stderr.println(eventJson);
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
index 3fcd836feb6..7630f176b4d 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/FailedHandlerGuard.java
@@ -44,7 +44,9 @@
  * Performs logging of failed signals handlers or fails the test
  * depending upon the current context exception tolerance.
  */
-public final class FailedHandlerGuard extends AbstractEventSubscriber implements DiagnosticLogging {
+public final class FailedHandlerGuard
+        extends AbstractEventSubscriber
+        implements DiagnosticLogging {
 
     private HandlerFailureTolerance tolerance = HandlerFailureTolerance.RAISE_AND_FAIL;
 
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
index fac7a68a197..46da496691a 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/MessageCollector.java
@@ -51,13 +51,13 @@
  * Abstract base for message listeners that collect messages posted to a bus.
  *
  * @param <I>
- *         the type of the message identifiers
+ *         the type of the signal identifiers
  * @param <T>
- *         the type of the outer objects of messages
+ *         the type of the collected signals
  * @param <E>
  *         the type of the message envelopes
  */
-public abstract class MessageCollector<I extends SignalId,
+abstract class MessageCollector<I extends SignalId,
                                 T extends Signal<I, ?, ?>,
                                 E extends MessageEnvelope<I, T, ?>>
         implements Listener<E> {
@@ -87,14 +87,14 @@ public final void accept(E envelope) {
     }
 
     /**
-     * Obtains immutable list with outer objects of messages collected so far.
+     * Obtains an immutable list with outer objects of messages collected so far.
      */
     public final ImmutableList<T> all() {
         return ImmutableList.copyOf(outerObjects);
     }
 
     /**
-     * Obtains immutable list with outer objects of messages belonging to the passed tenant.
+     * Obtains an immutable list with outer objects of messages belonging to the passed tenant.
      */
     public final ImmutableList<T> ofTenant(TenantId tenantId) {
         checkNotNull(tenantId);
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
index 89c02625bd7..d52d69939ff 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
@@ -28,17 +28,18 @@
 
 import com.google.common.collect.ImmutableSet;
 import io.spine.server.BoundedContext;
-import io.spine.server.BoundedContextBuilder;
-import io.spine.server.bus.Listener;
 import io.spine.server.event.EventDispatcher;
-import io.spine.server.type.CommandEnvelope;
-import io.spine.server.type.EventEnvelope;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Set;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+/**
+ * An implementation of {@link BoundedContext.Probe} which is used by
+ * {@link io.spine.testing.server.blackbox.BlackBox BlackBox} to collect
+ * commands and events produced by a {@link BoundedContext} being tested.
+ */
 public class Probe implements BoundedContext.Probe {
 
     private @Nullable BoundedContext context;
@@ -60,6 +61,9 @@ public class Probe implements BoundedContext.Probe {
      */
     private final FailedHandlerGuard failedHandlerGuard;
 
+    /**
+     * Creates a new instance.
+     */
     public Probe() {
         this.commands = new CommandCollector();
         this.events = new EventCollector();
@@ -77,26 +81,21 @@ public boolean isRegistered() {
         return context != null;
     }
 
-    public CommandCollector commands() {
-        return commands;
-    }
-
-    public EventCollector events() {
-        return events;
-    }
-
+    /**
+     * Obtains a {@link FailedHandlerGuard} instance used by this probe.
+     */
     public FailedHandlerGuard failedHandlerGuard() {
         return failedHandlerGuard;
     }
 
     @Override
-    public Listener<CommandEnvelope> commandListener() {
-        return commands();
+    public CommandCollector commandListener() {
+        return commands;
     }
 
     @Override
-    public Listener<EventEnvelope> eventListener() {
-        return events();
+    public EventCollector eventListener() {
+        return events;
     }
 
     @Override
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
index 0bf3d522413..afd6a40519d 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/package-info.java
@@ -28,10 +28,12 @@
  * This package contains diagnostic utilities for
  * {@link io.spine.server.BoundedContext io.spine.server.BoundedContext}.
  */
+@Internal
 @CheckReturnValue
 @ParametersAreNonnullByDefault
 package io.spine.testing.server.blackbox.probe;
 
 import com.google.errorprone.annotations.CheckReturnValue;
+import io.spine.annotation.Internal;
 
 import javax.annotation.ParametersAreNonnullByDefault;

From 4e69262cf35da2a55af3e398e36f5f7fc9d34813 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 00:17:13 +0000
Subject: [PATCH 09/32] Convert tests of `BoundedContext` to Kotlin

Also:
 * Add ext. fun for `BoundedContext`.
---
 .../java/io/spine/server/BoundedContext.java  |  11 +
 .../io/spine/server/BoundedContextExts.kt     |  36 ++
 .../com/example/ForeignContextConfig.java     |   2 +-
 .../io/spine/server/BoundedContextSpec.kt     | 489 +++++++++++++++++
 .../io/spine/server/BoundedContextTest.java   | 518 ------------------
 5 files changed, 537 insertions(+), 519 deletions(-)
 create mode 100644 server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
 create mode 100644 server/src/test/java/io/spine/server/BoundedContextSpec.kt
 delete mode 100644 server/src/test/java/io/spine/server/BoundedContextTest.java

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 10825c1934d..ca45516c2ba 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -577,6 +577,17 @@ public final void removeProbe() {
         probe = null;
     }
 
+    /**
+     * Obtains the currently installed {@link Probe} or {@link Optional#empty()} if no probe
+     * is installed.
+     */
+    public final Optional<Probe> probe() {
+        return Optional.ofNullable(probe);
+    }
+
+    /**
+     * Returns {@code true} if a {@link Probe} is installed, {@code false} otherwise.
+     */
     public final boolean hasProbe() {
         return probe != null;
     }
diff --git a/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt b/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
new file mode 100644
index 00000000000..a412fc12bad
--- /dev/null
+++ b/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2023, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.server
+
+import io.spine.base.EntityState
+import io.spine.server.entity.Entity
+
+public inline fun <reified E: Entity<*, *>> BoundedContext.hasEntitiesOfType(): Boolean =
+    hasEntitiesOfType(E::class.java)
+
+public inline fun <reified S: EntityState<*>> BoundedContext.hasEntitiesWithState(): Boolean =
+    hasEntitiesWithState(S::class.java)
diff --git a/server/src/test/java/com/example/ForeignContextConfig.java b/server/src/test/java/com/example/ForeignContextConfig.java
index 10256118481..d96f2fa2030 100644
--- a/server/src/test/java/com/example/ForeignContextConfig.java
+++ b/server/src/test/java/com/example/ForeignContextConfig.java
@@ -46,7 +46,7 @@
  * Test environment class for testing {@code BoundedContext} configuration from
  * outside the framework.
  *
- * @see io.spine.server.BoundedContextTest.RestrictRegistrationCalls
+ * @see io.spine.server.BoundedContextSpec.RestrictRegistrationCalls
  */
 public final class ForeignContextConfig {
 
diff --git a/server/src/test/java/io/spine/server/BoundedContextSpec.kt b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
new file mode 100644
index 00000000000..b975026c98c
--- /dev/null
+++ b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
@@ -0,0 +1,489 @@
+/*
+ * Copyright 2022, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package io.spine.server
+
+import com.example.ForeignContextConfig
+import com.google.common.collect.ImmutableSet
+import com.google.common.collect.Sets
+import com.google.common.testing.EqualsTester
+import com.google.common.truth.Truth.assertThat
+import com.google.common.truth.Truth8
+import io.kotest.matchers.collections.shouldBeEmpty
+import io.kotest.matchers.collections.shouldContain
+import io.kotest.matchers.collections.shouldNotBeEmpty
+import io.kotest.matchers.collections.shouldNotContain
+import io.kotest.matchers.optional.shouldBeEmpty
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+import io.spine.annotation.Internal
+import io.spine.core.BoundedContextName
+import io.spine.core.BoundedContextNames
+import io.spine.logging.Level.Companion.DEBUG
+import io.spine.logging.toJavaLogging
+import io.spine.option.EntityOption
+import io.spine.server.bc.given.AnotherProjectAggregate
+import io.spine.server.bc.given.FinishedProjectProjection
+import io.spine.server.bc.given.ProjectAggregate
+import io.spine.server.bc.given.ProjectCreationRepository
+import io.spine.server.bc.given.ProjectProcessManager
+import io.spine.server.bc.given.ProjectProjection
+import io.spine.server.bc.given.ProjectRemovalProcman
+import io.spine.server.bc.given.ProjectReport
+import io.spine.server.bc.given.SecretProjectRepository
+import io.spine.server.bc.given.TestEventSubscriber
+import io.spine.server.entity.Entity
+import io.spine.server.entity.Repository
+import io.spine.system.server.SystemClient
+import io.spine.system.server.SystemContext
+import io.spine.test.bc.Project
+import io.spine.test.bc.SecretProject
+import io.spine.testing.TestValues
+import io.spine.testing.logging.Interceptor
+import io.spine.testing.server.model.ModelTests
+import java.util.function.BooleanSupplier
+import java.util.logging.Level
+import java.util.stream.Stream
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import org.junit.jupiter.api.function.Executable
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
+
+/**
+ * Tests of [BoundedContext].
+ *
+ * Messages used in this test suite are defined in:
+ *
+ *  * `spine/test/bc/project.proto` - data types
+ *  * `spine/test/bc/commands.proto` — commands
+ *  * `spine/test/bc/events.proto` — events.
+ */
+@DisplayName("`BoundedContext` should")
+internal class BoundedContextSpec {
+    private val subscriber = TestEventSubscriber()
+
+    private lateinit var context: BoundedContext
+
+    private var handlersRegistered = false
+
+    @BeforeEach
+    fun setUp() {
+        ModelTests.dropAllModels()
+        context = BoundedContextBuilder.assumingTests(true).build()
+    }
+
+    @AfterEach
+    fun tearDown() {
+        if (handlersRegistered) {
+            context.eventBus()
+                .unregister(subscriber)
+        }
+        context.close()
+    }
+
+    /** Registers all test repositories, handlers, etc.  */
+    private fun registerAll() {
+        context.register(DefaultRepository.of(ProjectAggregate::class.java))
+        context.eventBus().register(subscriber)
+        handlersRegistered = true
+    }
+
+    @Nested
+    @DisplayName("provide access to")
+    @Suppress("TestFunctionName") // For readability of methods named after class names.
+    internal inner class Return {
+
+        @Test
+        fun EventBus() {
+            context.eventBus() shouldNotBe null
+        }
+
+        @Test
+        fun IntegrationBroker() {
+            context.internalAccess().broker() shouldNotBe null
+        }
+
+        @Test
+        fun CommandDispatcher() {
+            context.commandBus() shouldNotBe null
+        }
+
+        @Test
+        fun `multitenancy state`() {
+            BoundedContextBuilder.assumingTests(true).build().use {
+                it.isMultitenant shouldBe true
+            }
+        }
+    }
+
+    @Nested
+    @DisplayName("register")
+    @Suppress("TestFunctionName") // For readability of methods named after class names.
+    internal inner class Register {
+
+        @Test
+        fun AggregateRepository() =
+            registerAndAssertRepository(ProjectAggregate::class.java)
+
+        @Test
+        fun ProcessManagerRepository() =
+            registerAndAssertRepository(ProjectProcessManager::class.java)
+
+        @Test
+        fun ProjectionRepository() =
+            registerAndAssertRepository(ProjectReport::class.java)
+
+        /**
+         * Registers a [DefaultRepository] for the given entity class and asserts that
+         * the context has entities of the given type.
+         */
+        private fun <I, E : Entity<I, *>> registerAndAssertRepository(cls: Class<E>) {
+            context.register(DefaultRepository.of(cls))
+            context.hasEntitiesOfType(cls) shouldBe true
+        }
+
+        @Test
+        fun `a 'DefaultRepository' via passed entity class`() {
+            context.register(ProjectAggregate::class.java)
+            context.hasEntitiesOfType<ProjectAggregate>() shouldBe true
+        }
+    }
+
+    @Nested
+    @DisplayName("test presence of entities by")
+    internal inner class EntityTypePresence {
+
+        @Nested
+        @DisplayName("entity state class for")
+        internal inner class ByEntityStateClass {
+
+            @Test
+            fun `visible entities`() {
+                context.register(ProjectAggregate::class.java)
+                context.hasEntitiesWithState<Project>() shouldBe true
+            }
+
+            @Test
+            @DisplayName("invisible entities")
+            fun invisible() {
+                context.register(SecretProjectRepository())
+                context.hasEntitiesWithState<SecretProject>() shouldBe true
+            }
+        }
+
+        @Nested
+        @DisplayName("entity class for")
+        internal inner class ByEntityClass {
+
+            @Test
+            fun `visible entities`() {
+                context.register(ProjectAggregate::class.java)
+                context.hasEntitiesOfType<ProjectAggregate>() shouldBe true
+            }
+
+            @Test
+            fun `invisible entities`() {
+                // Process Managers are invisible by default.
+                context.register(ProjectProcessManager::class.java)
+
+                context.hasEntitiesOfType<ProjectProcessManager>() shouldBe true
+            }
+        }
+    }
+
+    @Test
+    fun `propagate registered repositories to 'Stand'`() {
+        val context = BoundedContextBuilder.assumingTests().build()
+        val stand = context.stand()
+
+        val repo = DefaultRepository.of(ProjectAggregate::class.java)
+        val stateType = repo.entityStateType()
+
+        // No type until registration at the context.
+        stand.exposedTypes() shouldNotContain stateType
+
+        context.register(repo)
+
+        // After registration, the type is exposed.
+        stand.exposedTypes() shouldContain stateType
+    }
+
+    @ParameterizedTest
+    @MethodSource("sameStateRepositories")
+    fun `not allow two entity repositories with entities of same state`(
+        firstRepo: Repository<*, *>, secondRepo: Repository<*, *>
+    ) {
+        context.register(firstRepo)
+        assertThrows<IllegalStateException> {
+            context.register(secondRepo)
+        }
+    }
+
+    @Test
+    fun `assign storage during registration if repository does not have one`() {
+        val repository = DefaultRepository.of(ProjectAggregate::class.java)
+        context.register(repository)
+        repository.storageAssigned() shouldBe true
+    }
+
+    @Nested
+    @DisplayName("assign own multitenancy state to")
+    @Suppress("TestFunctionName") // for readability of methods named after class names.
+    internal inner class AssignMultitenancyState {
+
+        private lateinit var context: BoundedContext
+
+        @Test
+        fun CommandBus() {
+            context = multiTenant()
+            assertMultitenancyEqual(
+                { context.isMultitenant },
+                { context.commandBus().isMultitenant })
+
+            context = singleTenant()
+            assertMultitenancyEqual(
+                { context.isMultitenant },
+                { context.commandBus().isMultitenant })
+        }
+
+        @Test
+        fun Stand() {
+            context = multiTenant()
+
+            assertMultitenancyEqual(
+                { context.isMultitenant },
+                { context.stand().isMultitenant })
+
+            context = singleTenant()
+
+            assertMultitenancyEqual(
+                { context.isMultitenant },
+                { context.stand().isMultitenant })
+        }
+
+        private fun assertMultitenancyEqual(s1: BooleanSupplier, s2: BooleanSupplier) {
+            s1.asBoolean shouldBe s2.asBoolean
+        }
+
+        private fun multiTenant(): BoundedContext =
+            BoundedContextBuilder.assumingTests(true).build()
+
+        private fun singleTenant(): BoundedContext =
+            BoundedContextBuilder.assumingTests(false).build()
+    }
+
+    /**
+     * Simply checks that the result isn't empty to cover the integration with
+     * [VisibilityGuard].
+     *
+     * See [tests of VisibilityGuard][io.spine.server.entity.VisibilityGuardTest]
+     * for how visibility filtering works.
+     */
+    @Test
+    fun `obtain entity types by visibility`() {
+        context.stateTypes(EntityOption.Visibility.FULL).shouldBeEmpty()
+        registerAll()
+        context.stateTypes(EntityOption.Visibility.FULL).shouldNotBeEmpty()
+    }
+
+    @Test
+    fun `throw 'ISE' when obtaining a repository for non-registered entity state class`() {
+        // Attempt to get a repository without registering.
+        assertThrows<IllegalStateException> {
+            context.internalAccess().findRepository(Project::class.java)
+        }
+    }
+
+    @Test
+    fun `not expose invisible aggregates`() {
+        ModelTests.dropAllModels()
+        context.register(SecretProjectRepository())
+        context.internalAccess().findRepository(SecretProject::class.java).shouldBeEmpty()
+    }
+
+    @Test
+    @DisplayName("prohibit 3rd-party descendants")
+    fun `prohibit 3rd-party descendants`() {
+        assertThrows<IllegalStateException> {
+            object : BoundedContext(BoundedContextBuilder.assumingTests()) {
+                @Internal
+                override fun systemClient(): SystemClient = TestValues.nullRef()
+            }
+        }
+    }
+
+    @Nested
+    @DisplayName("when closing")
+    internal inner class ClosingContext {
+        private val contextName: BoundedContextName = BoundedContextNames.newName("TestDomain")
+        private val systemContextName: BoundedContextName = contextName.toSystem()
+        private val debugLevel: Level = DEBUG.toJavaLogging()
+
+        private lateinit var domainInterceptor: Interceptor
+        private lateinit var systemInterceptor: Interceptor
+
+        @BeforeEach
+        fun closeContext() {
+            val context = BoundedContext.singleTenant(contextName.value).build()
+            domainInterceptor = Interceptor(DomainContext::class.java, debugLevel)
+            domainInterceptor.intercept()
+            systemInterceptor = Interceptor(SystemContext::class.java, debugLevel)
+            systemInterceptor.intercept()
+
+            context.close()
+        }
+
+        @AfterEach
+        fun releaseInterceptors() {
+            domainInterceptor.release()
+            systemInterceptor.release()
+        }
+
+        @Test
+        fun `log its closing`() {
+            domainInterceptor.assertLog().record().run {
+                hasLevelThat().isEqualTo(debugLevel)
+                hasMessageThat().contains(contextName.value)
+            }
+        }
+
+        @Test
+        fun `close its System context`() {
+            systemInterceptor.assertLog().record().run {
+                hasLevelThat().isEqualTo(debugLevel)
+                hasMessageThat().contains(systemContextName.value)
+            }
+        }
+    }
+
+    @Test
+    fun `return its name in 'toString()'`() {
+        val name = TestValues.randomString()
+        BoundedContext.singleTenant(name).build().use {
+            it.toString() shouldBe name
+        }
+    }
+
+    @Nested
+    @DisplayName("do not allow registration calls from outside the `io.spine.server` package for")
+    @Suppress("TestFunctionName") // For readability of methods named after class names.
+    internal inner class RestrictRegistrationCalls {
+
+        @Test
+        fun Repository() = assertThrowsOn {
+            ForeignContextConfig.repositoryRegistration()
+        }
+
+        @Test
+        fun CommandDispatcher() = assertThrowsOn {
+            ForeignContextConfig.commandDispatcherRegistration()
+        }
+
+        @Test
+        fun EventDispatcher() = assertThrowsOn {
+            ForeignContextConfig.eventDispatcherRegistration()
+        }
+
+        private fun assertThrowsOn(executable: Executable) {
+            Assertions.assertThrows(SecurityException::class.java, executable)
+        }
+    }
+
+    @Test
+    fun `be equal to another context by its name`() {
+        val c1 = BoundedContext.singleTenant("One").build()
+        val c2 = BoundedContext.singleTenant("Two").build()
+        val c1m = BoundedContext.multitenant("One").build()
+        val c2m = BoundedContext.multitenant("Two").build()
+
+        EqualsTester()
+            .addEqualityGroup(c1, c1m)
+            .addEqualityGroup(c2, c2m)
+            .testEquals()
+    }
+
+    @Test
+    fun `be comparable by its name`() {
+        val c1 = BoundedContext.singleTenant("1").build()
+        val c2 = BoundedContext.singleTenant("2").build()
+
+        assertThat(c1).isLessThan(c2)
+        assertThat(c2).isGreaterThan(c1)
+        assertThat(c1).isEqualTo(BoundedContext.multitenant("1").build())
+    }
+
+    companion object {
+
+        /**
+         * Returns all combinations of repositories that manage entities of the same state.
+         *
+         *
+         * To check whether a [io.spine.server.BoundedContext] really throws
+         * an `IllegalStateException` upon an attempt to register a repository that manages an
+         * entity of a state that a registered entity repository is already managing,
+         * all combinations of entities that take state as a type parameter need to be checked.
+         *
+         * This method returns a stream of pairs of all such combinations, which is a Cartesian
+         * product of:
+         *
+         *  * [Process Manager][io.spine.server.procman.ProcessManagerRepository];
+         *  * [Aggregate][io.spine.server.aggregate.AggregateRepository];
+         *  * [Projection][io.spine.server.projection.ProjectionRepository].
+         *
+         * All the returned repositories manage entities of the same state type.
+         */
+        @Suppress("unused") /* A method source. */
+        @JvmStatic
+        fun sameStateRepositories(): Stream<Arguments> {
+            val repositories: Set<Repository<*, *>> =
+                ImmutableSet.of<Repository<*, *>>(
+                    DefaultRepository.of(ProjectAggregate::class.java),
+                    DefaultRepository.of(ProjectProjection::class.java),
+                    ProjectCreationRepository()
+                )
+
+            val sameStateRepositories: Set<Repository<*, *>> =
+                ImmutableSet.of<Repository<*, *>>(
+                    DefaultRepository.of(AnotherProjectAggregate::class.java),
+                    DefaultRepository.of(FinishedProjectProjection::class.java),
+                    DefaultRepository.of(ProjectRemovalProcman::class.java)
+                )
+
+            val cartesianProduct = Sets.cartesianProduct(repositories, sameStateRepositories)
+            val result = cartesianProduct.stream()
+                .map { repos: List<Repository<*, *>> ->
+                    Arguments.of(repos[0], repos[1])
+                }
+            return result
+        }
+    }
+}
diff --git a/server/src/test/java/io/spine/server/BoundedContextTest.java b/server/src/test/java/io/spine/server/BoundedContextTest.java
deleted file mode 100644
index b5df2aefa63..00000000000
--- a/server/src/test/java/io/spine/server/BoundedContextTest.java
+++ /dev/null
@@ -1,518 +0,0 @@
-/*
- * Copyright 2022, TeamDev. All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Redistribution and use in source and/or binary forms, with or without
- * modification, must retain the above copyright notice and the following
- * disclaimer.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-package io.spine.server;
-
-import com.example.ForeignContextConfig;
-import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Sets;
-import com.google.common.testing.EqualsTester;
-import io.spine.annotation.Internal;
-import io.spine.core.BoundedContextName;
-import io.spine.option.EntityOption;
-import io.spine.server.bc.given.AnotherProjectAggregate;
-import io.spine.server.bc.given.FinishedProjectProjection;
-import io.spine.server.bc.given.ProjectAggregate;
-import io.spine.server.bc.given.ProjectCreationRepository;
-import io.spine.server.bc.given.ProjectProcessManager;
-import io.spine.server.bc.given.ProjectProjection;
-import io.spine.server.bc.given.ProjectRemovalProcman;
-import io.spine.server.bc.given.ProjectReport;
-import io.spine.server.bc.given.SecretProjectRepository;
-import io.spine.server.bc.given.TestEventSubscriber;
-import io.spine.server.entity.Entity;
-import io.spine.server.entity.Repository;
-import io.spine.system.server.SystemClient;
-import io.spine.system.server.SystemContext;
-import io.spine.test.bc.Project;
-import io.spine.test.bc.SecretProject;
-import io.spine.testing.logging.Interceptor;
-import io.spine.testing.server.model.ModelTests;
-import org.junit.jupiter.api.AfterEach;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.DisplayName;
-import org.junit.jupiter.api.Nested;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.function.Executable;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
-import org.junit.jupiter.params.provider.MethodSource;
-
-import java.util.Set;
-import java.util.function.BooleanSupplier;
-import java.util.logging.Level;
-import java.util.stream.Stream;
-
-import static com.google.common.truth.Truth.assertThat;
-import static com.google.common.truth.Truth8.assertThat;
-import static io.spine.core.BoundedContextNames.newName;
-import static io.spine.logging.JvmLoggerKt.toJavaLogging;
-import static io.spine.testing.TestValues.nullRef;
-import static io.spine.testing.TestValues.randomString;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-/**
- * Tests of {@link BoundedContext}.
- *
- * <p>Messages used in this test suite are defined in:
- * <ul>
- *     <li>{@code spine/test/bc/project.proto} - data types
- *     <li>{@code spine/test/bc/commands.proto} — commands
- *     <li>{@code spine/test/bc/events.proto} — events.
- * </ul>
- */
-@DisplayName("`BoundedContext` should")
-class BoundedContextTest {
-
-    private final TestEventSubscriber subscriber = new TestEventSubscriber();
-
-    private BoundedContext context;
-
-    private boolean handlersRegistered = false;
-
-    @BeforeEach
-    void setUp() {
-        ModelTests.dropAllModels();
-        context = BoundedContextBuilder.assumingTests(true).build();
-    }
-
-    @AfterEach
-    void tearDown() throws Exception {
-        if (handlersRegistered) {
-            context.eventBus()
-                   .unregister(subscriber);
-        }
-        context.close();
-    }
-
-    /** Registers all test repositories, handlers etc. */
-    private void registerAll() {
-        context.register(DefaultRepository.of(ProjectAggregate.class));
-        context.eventBus()
-               .register(subscriber);
-        handlersRegistered = true;
-    }
-
-    @Nested
-    @DisplayName("return")
-    class Return {
-
-        @Test
-        @DisplayName("`EventBus`")
-        void eventBus() {
-            assertNotNull(context.eventBus());
-        }
-
-        @Test
-        @DisplayName("`IntegrationBroker`")
-        void integrationBroker() {
-            assertNotNull(context.internalAccess()
-                                 .broker());
-        }
-
-        @Test
-        @DisplayName("`CommandDispatcher`")
-        void commandDispatcher() {
-            assertNotNull(context.commandBus());
-        }
-
-        @Test
-        @DisplayName("multitenancy state")
-        void ifSetMultitenant() {
-            var bc = BoundedContextBuilder.assumingTests(true).build();
-            assertTrue(bc.isMultitenant());
-        }
-    }
-
-    @Nested
-    @DisplayName("register")
-    class Register {
-
-        @Test
-        @DisplayName("`AggregateRepository`")
-        void aggregateRepository() {
-            registerAndAssertRepository(ProjectAggregate.class);
-        }
-
-        @Test
-        @DisplayName("`ProcessManagerRepository`")
-        void processManagerRepository() {
-            registerAndAssertRepository(ProjectProcessManager.class);
-        }
-
-        @Test
-        @DisplayName("`ProjectionRepository`")
-        void projectionRepository() {
-            registerAndAssertRepository(ProjectReport.class);
-        }
-
-        <I, E extends Entity<I, ?>> void registerAndAssertRepository(Class<E> cls) {
-            context.register(DefaultRepository.of(cls));
-            assertTrue(context.hasEntitiesOfType(cls));
-        }
-
-        @Test
-        @DisplayName("`DefaultRepository` via passed entity class")
-        void entityClass() {
-            context.register(ProjectAggregate.class);
-            assertTrue(context.hasEntitiesOfType(ProjectAggregate.class));
-        }
-    }
-
-    @Nested
-    @DisplayName("test presence of entities by")
-    class EntityTypePresence {
-
-        @Nested
-        @DisplayName("entity state class for")
-        class ByEntityStateClass {
-
-            @Test
-            @DisplayName("visible entities")
-            void visible() {
-                context.register(ProjectAggregate.class);
-                assertTrue(context.hasEntitiesWithState(Project.class));
-            }
-
-            @Test
-            @DisplayName("invisible entities")
-            void invisible() {
-                context.register(new SecretProjectRepository());
-                assertTrue(context.hasEntitiesWithState(SecretProject.class));
-            }
-        }
-
-        @Nested
-        @DisplayName("entity class for")
-        class ByEntityClass {
-
-            @Test
-            @DisplayName("visible entities")
-            void visible() {
-                context.register(ProjectAggregate.class);
-                assertTrue(context.hasEntitiesOfType(ProjectAggregate.class));
-            }
-
-            @Test
-            @DisplayName("invisible entities")
-            void invisible() {
-                // Process Managers are invisible by default.
-                context.register(ProjectProcessManager.class);
-                assertTrue(context.hasEntitiesOfType(ProjectProcessManager.class));
-            }
-        }
-    }
-
-    @Test
-    @DisplayName("propagate registered repositories to `Stand`")
-    void propagateRepositoriesToStand() {
-        var context = BoundedContextBuilder.assumingTests().build();
-        var stand = context.stand();
-
-        var repo =
-                DefaultRepository.of(ProjectAggregate.class);
-        var stateType = repo.entityStateType();
-
-        assertThat(stand.exposedTypes())
-                .doesNotContain(stateType);
-
-        context.register(repo);
-
-        assertThat(stand.exposedTypes())
-                .contains(stateType);
-    }
-
-    @ParameterizedTest
-    @MethodSource("sameStateRepositories")
-    @DisplayName("not allow two entity repositories with entities of same state")
-    void throwOnSameEntityState(Repository<?, ?> firstRepo,
-                                Repository<?, ?> secondRepo) {
-        context.register(firstRepo);
-        assertThrows(IllegalStateException.class, () -> context.register(secondRepo));
-    }
-
-    /**
-     * Returns all combinations of repositories that manage entities of the same state.
-     *
-     * <p>To check whether a {@link io.spine.server.BoundedContext} really throws
-     * an {@code IllegalStateException} upon an attempt to register a repository that manages an
-     * entity of a state that a registered entity repository is already managing, all combinations
-     * of entities that take state as a type parameter need to be checked.
-     *
-     * <p>This method returns a stream of pairs of all such combinations, which is a Cartesian
-     * product of:
-     * <ul>
-     *     <li>{@linkplain io.spine.server.procman.ProcessManagerRepository process manager};
-     *     <li>{@linkplain io.spine.server.aggregate.AggregateRepository aggregate};
-     *     <li>{@linkplain io.spine.server.projection.ProjectionRepository projection}.
-     * </ul>
-     * All of the returned repositories manage entities of the same state type.
-     */
-    @SuppressWarnings("unused") /* A method source. */
-    private static Stream<Arguments> sameStateRepositories() {
-        Set<Repository<?, ?>> repositories =
-                ImmutableSet.of(DefaultRepository.of(ProjectAggregate.class),
-                                DefaultRepository.of(ProjectProjection.class),
-                                new ProjectCreationRepository());
-
-        Set<Repository<?, ?>> sameStateRepositories =
-                ImmutableSet.of(DefaultRepository.of(AnotherProjectAggregate.class),
-                                DefaultRepository.of(FinishedProjectProjection.class),
-                                DefaultRepository.of(ProjectRemovalProcman.class));
-
-        var cartesianProduct =
-                Sets.cartesianProduct(repositories, sameStateRepositories);
-        var result =
-                cartesianProduct.stream()
-                                .map(repos -> Arguments.of(repos.get(0), repos.get(1)));
-        return result;
-    }
-
-    @Test
-    @DisplayName("assign storage during registration if repository does not have one")
-    void setStorageOnRegister() {
-        var repository = DefaultRepository.of(ProjectAggregate.class);
-        context.register(repository);
-        assertTrue(repository.storageAssigned());
-    }
-
-    @Nested
-    @DisplayName("assign own multitenancy state to")
-    class AssignMultitenancyState {
-
-        private BoundedContext context;
-
-        @Test
-        @DisplayName("`CommandBus`")
-        void toCommandBus() {
-            context = multiTenant();
-            assertMultitenancyEqual(context::isMultitenant, context.commandBus()::isMultitenant);
-
-            context = singleTenant();
-            assertMultitenancyEqual(context::isMultitenant, context.commandBus()::isMultitenant);
-        }
-
-        @Test
-        @DisplayName("`Stand`")
-        void toStand() {
-            context = multiTenant();
-
-            assertMultitenancyEqual(context::isMultitenant, context.stand()::isMultitenant);
-
-            context = singleTenant();
-
-            assertMultitenancyEqual(context::isMultitenant, context.stand()::isMultitenant);
-        }
-
-        private void assertMultitenancyEqual(BooleanSupplier s1, BooleanSupplier s2) {
-            assertThat(s1.getAsBoolean())
-                    .isEqualTo(s2.getAsBoolean());
-        }
-
-        private BoundedContext multiTenant() {
-            return BoundedContextBuilder
-                    .assumingTests(true)
-                    .build();
-        }
-
-        private BoundedContext singleTenant() {
-            return BoundedContextBuilder
-                    .assumingTests(false)
-                    .build();
-        }
-    }
-
-    /**
-     * Simply checks that the result isn't empty to cover the integration with
-     * {@link VisibilityGuard VisibilityGuard}.
-     *
-     * <p>See {@linkplain io.spine.server.entity.VisibilityGuardTest tests of VisibilityGuard}
-     * for how visibility filtering works.
-     */
-    @Test
-    @DisplayName("obtain entity types by visibility")
-    void getEntityTypesByVisibility() {
-        assertThat(context.stateTypes(EntityOption.Visibility.FULL))
-                .isEmpty();
-
-        registerAll();
-
-        assertThat(context.stateTypes(EntityOption.Visibility.FULL))
-                .isNotEmpty();
-    }
-
-    @Test
-    @DisplayName("throw `ISE` when obtaining a repository for non-registered entity state class")
-    void throwOnNoRepoRegistered() {
-        // Attempt to get a repository without registering.
-        assertThrows(IllegalStateException.class,
-                     () -> context.internalAccess()
-                                  .findRepository(Project.class));
-    }
-
-    @Test
-    @DisplayName("not expose invisible aggregates")
-    void notExposeInvisibleAggregates() {
-        ModelTests.dropAllModels();
-
-        context.register(new SecretProjectRepository());
-
-        assertThat(context.internalAccess()
-                          .findRepository(SecretProject.class))
-                .isEmpty();
-    }
-
-    @Test
-    @DisplayName("prohibit 3rd-party descendants")
-    void noExternalDescendants() {
-        assertThrows(
-                IllegalStateException.class,
-                () ->
-                new BoundedContext(BoundedContextBuilder.assumingTests()) {
-
-                    @Internal
-                    @Override
-                    public SystemClient systemClient() {
-                        return nullRef();
-                    }
-                }
-        );
-    }
-
-    @Nested
-    @DisplayName("when closing")
-    class ClosingContext {
-
-        private final BoundedContextName contextName = newName("TestDomain");
-        private final BoundedContextName systemContextName = contextName.toSystem();
-        private final Level debugLevel = toJavaLogging(io.spine.logging.Level.Companion.getDEBUG());
-
-        private Interceptor domainInterceptor;
-        private Interceptor systemInterceptor;
-
-        @BeforeEach
-        void closeContext() throws Exception {
-            var context = BoundedContext.singleTenant(contextName.getValue()).build();
-            domainInterceptor = new Interceptor(DomainContext.class, debugLevel);
-            domainInterceptor.intercept();
-            systemInterceptor = new Interceptor(SystemContext.class, debugLevel);
-            systemInterceptor.intercept();
-
-            context.close();
-        }
-
-        @AfterEach
-        void releaseInterceptors() {
-            domainInterceptor.release();
-            systemInterceptor.release();
-        }
-
-        @Test
-        @DisplayName("log its closing")
-        void logClosing() {
-            var assertDomainLog = domainInterceptor.assertLog().record();
-            assertDomainLog.hasLevelThat()
-                           .isEqualTo(debugLevel);
-            assertDomainLog.hasMessageThat()
-                           .contains(contextName.getValue());
-        }
-
-        @Test
-        @DisplayName("close its System context")
-        void closeSystem() {
-            var assertSystemLog = systemInterceptor.assertLog().record();
-            assertSystemLog.hasLevelThat()
-                           .isEqualTo(debugLevel);
-            assertSystemLog.hasMessageThat()
-                           .contains(systemContextName.getValue());
-        }
-    }
-
-    @Test
-    @DisplayName("return its name in `toString()`")
-    void stringForm() {
-        var name = randomString();
-
-        assertThat(BoundedContext.singleTenant(name)
-                                 .build()
-                                 .toString())
-                .isEqualTo(name);
-    }
-
-    @Nested
-    @DisplayName("do not allow registration calls from outside the `io.spine.server` package for")
-    class RestrictRegistrationCalls {
-
-        @Test
-        @DisplayName("`Repository`")
-        void forRepository() {
-            assertThrowsOn(ForeignContextConfig::repositoryRegistration);
-        }
-
-        @Test
-        @DisplayName("`CommandDispatcher`")
-        void forCommandDispatcher() {
-            assertThrowsOn(ForeignContextConfig::commandDispatcherRegistration);
-        }
-
-        @Test
-        @DisplayName("`EventDispatcher`")
-        void forEventDispatcher() {
-            assertThrowsOn(ForeignContextConfig::eventDispatcherRegistration);
-        }
-
-        private void assertThrowsOn(Executable executable) {
-            assertThrows(SecurityException.class, executable);
-        }
-    }
-
-    @Test
-    @DisplayName("be equal to another context by its name")
-    void equality() {
-        var c1 = BoundedContext.singleTenant("One").build();
-        var c2 = BoundedContext.singleTenant("Two").build();
-        var c1m = BoundedContext.multitenant("One").build();
-        var c2m = BoundedContext.multitenant("Two").build();
-
-        new EqualsTester()
-                .addEqualityGroup(c1, c1m)
-                .addEqualityGroup(c2, c2m)
-                .testEquals();
-    }
-
-    @Test
-    @DisplayName("be comparable by its name")
-    void comparability() {
-        var c1 = BoundedContext.singleTenant("1").build();
-        var c2 = BoundedContext.singleTenant("2").build();
-
-        assertThat(c1).isLessThan(c2);
-        assertThat(c2).isGreaterThan(c1);
-        assertThat(c1).isEqualTo(BoundedContext.multitenant("1").build());
-    }
-}

From b952d8361df1de1fba474522b9b13c22036c97e7 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 04:57:04 +0000
Subject: [PATCH 10/32] Test internal access and probe

---
 .../java/io/spine/server/BoundedContext.java  |  16 +-
 .../spine/server/BoundedContextBuilder.java   |   5 +-
 .../main/java/io/spine/server/bus/Bus.java    |  36 +++-
 .../spine/server/bus/DispatcherRegistry.java  |   8 +-
 .../commandbus/CommandDispatcherRegistry.java |   2 +-
 .../io/spine/server/BoundedContextSpec.kt     | 191 ++++++++++++++----
 6 files changed, 203 insertions(+), 55 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index ca45516c2ba..4f900bde252 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -537,7 +537,7 @@ public String toString() {
     @Internal
     public final InternalAccess internalAccess() {
         Security.allowOnlyFrameworkServer();
-        return this.internalAccess;
+        return internalAccess;
     }
 
     /**
@@ -549,10 +549,22 @@ public int compareTo(BoundedContext another) {
         return name().value().compareTo(another.name().value());
     }
 
+    /**
+     * Installs the passed probe into this context.
+     *
+     * @see #hasProbe()
+     * @see #probe()
+     * @see #removeProbe()
+     * @throws IllegalStateException
+     *          if another probe is already installed
+     */
     public final void install(Probe probe) {
         checkNotNull(probe);
-        checkState(this.probe == null,
+        checkState(this.probe == null || probe.equals(this.probe),
                    "Probe is already installed (`%s`). Please remove previous probe first.", probe);
+        if (probe.equals(this.probe)) {
+            return;
+        }
         probe.registerWith(this);
         commandBus.add(probe.commandListener());
         eventBus.add(probe.eventListener());
diff --git a/server/src/main/java/io/spine/server/BoundedContextBuilder.java b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
index c4b0c76e669..e27a62a726f 100644
--- a/server/src/main/java/io/spine/server/BoundedContextBuilder.java
+++ b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
@@ -563,13 +563,14 @@ EventBus buildEventBus(BoundedContext context) {
      * Sets the action to be performed before the context is closed.
      *
      * <p>The action is performed after the context is closed, but before the
-     * {@linkplain BoundedContext#onClose() context's own action} is performed.
+     * {@linkplain BoundedContext#close() context's own action} is performed.
      *
      * @param consumer
      *         the action to perform
      */
-    public void setOnBeforeClose(Consumer<BoundedContext> consumer) {
+    public BoundedContextBuilder setOnBeforeClose(Consumer<BoundedContext> consumer) {
         this.onBeforeClose = checkNotNull(consumer);
+        return this;
     }
 
     @Nullable Consumer<BoundedContext> getOnBeforeClose() {
diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 7b21b549c4a..39179cd1171 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -54,15 +54,15 @@
 import static java.util.Collections.singleton;
 
 /**
- * Abstract base for buses.
+ * Abstract base for message buses.
  *
  * @param <T> the type of outer objects (containing messages of interest) that are posted to the bus
  * @param <E> the type of envelopes for outer objects used by this bus
  * @param <C> the type of message class
  * @param <D> the type of dispatches used by this bus
  */
-@SuppressWarnings("ClassWithTooManyMethods")    // It's OK.
 @Internal
+@SuppressWarnings("ClassWithTooManyMethods") // OK the abstract bus.
 public abstract class Bus<T extends Signal<?, ?, ?>,
                           E extends SignalEnvelope<?, T, ?>,
                           C extends MessageClass<? extends Message>,
@@ -75,6 +75,11 @@ public abstract class Bus<T extends Signal<?, ?, ?>,
     /** Listeners of the messages posted to the bus. */
     private final Listeners<E> listeners;
 
+    /**
+     * A supplier of the filter chain, which can be configured by the derived classes.
+     *
+     * @see #setupFilters(Iterable)
+     */
     private final Supplier<FilterChain<E>> filterChain;
 
     protected Bus(BusBuilder<?, T, E, C, D> builder) {
@@ -94,28 +99,38 @@ protected Bus(BusBuilder<?, T, E, C, D> builder) {
      */
     public void register(D dispatcher) {
         checkNotNull(dispatcher);
-        registry().register(dispatcher);
+        registry.register(dispatcher);
     }
 
     /**
-     * Unregisters dispatching for message classes of the passed dispatcher.
+     * Stops dispatching messages the given dispatcher.
      *
      * @param dispatcher the dispatcher to unregister
      */
     public void unregister(D dispatcher) {
         checkNotNull(dispatcher);
-        registry().unregister(dispatcher);
+        registry.unregister(dispatcher);
     }
 
+    /**
+     * Stops dispatching messages the given dispatcher delegate.
+     */
     public void unregister(DispatcherDelegate<C, E> delegate) {
         checkNotNull(delegate);
+        registry.unregister(delegate);
     }
 
+    /**
+     * Adds the passed listener to the bus.
+     */
     public void add(Listener<E> listener) {
         checkNotNull(listener);
         listeners.add(listener);
     }
 
+    /**
+     * Removes the passed listener from the bus.
+     */
     public void remove(Listener<E> listener) {
         checkNotNull(listener);
         listeners.remove(listener);
@@ -227,7 +242,7 @@ public final boolean isOpen() {
     @Override
     public void close() throws Exception {
         filterChain().close();
-        registry().unregisterAll();
+        registry.unregisterAll();
     }
 
     /**
@@ -343,8 +358,10 @@ private Optional<Ack> filter(E message) {
     /**
      * Posts each of the given envelopes into the bus and notifies the given observer.
      *
-     * @param envelopes the envelopes to post
-     * @param observer  the observer to be notified of the operation result
+     * @param envelopes
+     *         the envelopes to post
+     * @param observer
+     *         the observer to be notified of the operation result
      * @see #dispatch(SignalEnvelope)
      */
     @SuppressWarnings("ProhibitedExceptionThrown") // Rethrow a caught exception.
@@ -418,8 +435,7 @@ protected void onDispatched(SignalId signal) {
      */
     @OverridingMethodsMustInvokeSuper
     protected Iterable<BusFilter<E>> setupFilters(Iterable<BusFilter<E>> filters) {
-        return ImmutableList
-                .<BusFilter<E>>builder()
+        return ImmutableList.<BusFilter<E>>builder()
                 .add(new ValidatingFilter<>(validator()))
                 .add(new DeadMessageFilter<>(deadMessageHandler(), registry()))
                 .addAll(filters)
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java b/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
index 42a7f2fa3dd..e6c8c86df64 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherRegistry.java
@@ -54,10 +54,9 @@
  * @param <D>
  *         the type of the message dispatchers
  */
-public abstract class
-DispatcherRegistry<C extends MessageClass<? extends Message>,
-                   E extends MessageEnvelope<?, ?, ?>,
-                   D extends MessageDispatcher<C, E>> {
+public abstract class DispatcherRegistry<C extends MessageClass<? extends Message>,
+                                         E extends MessageEnvelope<?, ?, ?>,
+                                         D extends MessageDispatcher<C, E>> {
     /**
      * The map from a message class to one or more dispatchers of
      * messages of this class.
@@ -79,7 +78,6 @@ public void register(D dispatcher) {
     public void unregister(D dispatcher) {
         checkNotNull(dispatcher);
         checkNotEmpty(dispatcher);
-
         Set<C> messageClasses = dispatcher.messageClasses();
         for (var messageClass : messageClasses) {
             dispatchers.remove(messageClass, dispatcher);
diff --git a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
index 3317783068a..04a518cfd94 100644
--- a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
+++ b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
@@ -41,7 +41,7 @@
  *
  * <p>There can be only one dispatcher per command class.
  */
-class CommandDispatcherRegistry
+public final class CommandDispatcherRegistry
         extends DispatcherRegistry<CommandClass, CommandEnvelope, CommandDispatcher> {
 
     /**
diff --git a/server/src/test/java/io/spine/server/BoundedContextSpec.kt b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
index b975026c98c..17520d4cea6 100644
--- a/server/src/test/java/io/spine/server/BoundedContextSpec.kt
+++ b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
@@ -30,7 +30,6 @@ import com.google.common.collect.ImmutableSet
 import com.google.common.collect.Sets
 import com.google.common.testing.EqualsTester
 import com.google.common.truth.Truth.assertThat
-import com.google.common.truth.Truth8
 import io.kotest.matchers.collections.shouldBeEmpty
 import io.kotest.matchers.collections.shouldContain
 import io.kotest.matchers.collections.shouldNotBeEmpty
@@ -43,7 +42,8 @@ import io.spine.core.BoundedContextName
 import io.spine.core.BoundedContextNames
 import io.spine.logging.Level.Companion.DEBUG
 import io.spine.logging.toJavaLogging
-import io.spine.option.EntityOption
+import io.spine.option.EntityOption.Visibility.FULL
+import io.spine.server.BoundedContextBuilder.assumingTests
 import io.spine.server.bc.given.AnotherProjectAggregate
 import io.spine.server.bc.given.FinishedProjectProjection
 import io.spine.server.bc.given.ProjectAggregate
@@ -54,8 +54,12 @@ import io.spine.server.bc.given.ProjectRemovalProcman
 import io.spine.server.bc.given.ProjectReport
 import io.spine.server.bc.given.SecretProjectRepository
 import io.spine.server.bc.given.TestEventSubscriber
+import io.spine.server.bus.Listener
 import io.spine.server.entity.Entity
 import io.spine.server.entity.Repository
+import io.spine.server.event.EventDispatcher
+import io.spine.server.type.CommandEnvelope
+import io.spine.server.type.EventEnvelope
 import io.spine.system.server.SystemClient
 import io.spine.system.server.SystemContext
 import io.spine.test.bc.Project
@@ -64,6 +68,7 @@ import io.spine.testing.TestValues
 import io.spine.testing.logging.Interceptor
 import io.spine.testing.server.model.ModelTests
 import java.util.function.BooleanSupplier
+import java.util.function.Consumer
 import java.util.logging.Level
 import java.util.stream.Stream
 import org.junit.jupiter.api.AfterEach
@@ -72,6 +77,7 @@ import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
 import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
 import org.junit.jupiter.api.assertThrows
 import org.junit.jupiter.api.function.Executable
 import org.junit.jupiter.params.ParameterizedTest
@@ -88,6 +94,7 @@ import org.junit.jupiter.params.provider.MethodSource
  *  * `spine/test/bc/events.proto` — events.
  */
 @DisplayName("`BoundedContext` should")
+@Suppress("TestFunctionName") // For readability of methods named after class names.
 internal class BoundedContextSpec {
     private val subscriber = TestEventSubscriber()
 
@@ -98,19 +105,20 @@ internal class BoundedContextSpec {
     @BeforeEach
     fun setUp() {
         ModelTests.dropAllModels()
-        context = BoundedContextBuilder.assumingTests(true).build()
+        context = assumingTests(true).build()
     }
 
     @AfterEach
     fun tearDown() {
         if (handlersRegistered) {
-            context.eventBus()
-                .unregister(subscriber)
+            context.eventBus().unregister(subscriber)
+        }
+        if (context.isOpen) {
+            context.close()
         }
-        context.close()
     }
 
-    /** Registers all test repositories, handlers, etc.  */
+    /** Registers all test repositories, handlers, etc. */
     private fun registerAll() {
         context.register(DefaultRepository.of(ProjectAggregate::class.java))
         context.eventBus().register(subscriber)
@@ -119,35 +127,68 @@ internal class BoundedContextSpec {
 
     @Nested
     @DisplayName("provide access to")
-    @Suppress("TestFunctionName") // For readability of methods named after class names.
     internal inner class Return {
 
+        @Test
+        fun CommandBus() {
+            context.commandBus() shouldNotBe null
+        }
+
         @Test
         fun EventBus() {
             context.eventBus() shouldNotBe null
         }
 
         @Test
-        fun IntegrationBroker() {
-            context.internalAccess().broker() shouldNotBe null
+        fun ImportBus() {
+            context.importBus() shouldNotBe null
         }
 
         @Test
-        fun CommandDispatcher() {
-            context.commandBus() shouldNotBe null
+        fun Stand() {
+            context.stand() shouldNotBe null
         }
 
         @Test
         fun `multitenancy state`() {
-            BoundedContextBuilder.assumingTests(true).build().use {
+            assumingTests(true).build().use {
                 it.isMultitenant shouldBe true
             }
         }
+
+        @Test
+        fun SystemClient() {
+            context.systemClient() shouldNotBe null
+        }
+    }
+
+
+    @Nested
+    @DisplayName("provide internal secured access to")
+    inner class InternalAccess {
+
+        private val internalAccess = context.internalAccess()
+
+        @Test
+        fun IntegrationBroker() {
+            internalAccess.broker() shouldNotBe null
+        }
+
+        @Test
+        fun TenantIndex() {
+            internalAccess.tenantIndex() shouldNotBe null
+        }
+
+        @Test
+        fun `prohibiting access from outside of the 'server' package`() {
+            assertThrows<SecurityException> {
+                Consumer<Any> { context.internalAccess() }
+            }
+        }
     }
 
     @Nested
     @DisplayName("register")
-    @Suppress("TestFunctionName") // For readability of methods named after class names.
     internal inner class Register {
 
         @Test
@@ -222,7 +263,7 @@ internal class BoundedContextSpec {
 
     @Test
     fun `propagate registered repositories to 'Stand'`() {
-        val context = BoundedContextBuilder.assumingTests().build()
+        val context = assumingTests().build()
         val stand = context.stand()
 
         val repo = DefaultRepository.of(ProjectAggregate::class.java)
@@ -257,7 +298,6 @@ internal class BoundedContextSpec {
 
     @Nested
     @DisplayName("assign own multitenancy state to")
-    @Suppress("TestFunctionName") // for readability of methods named after class names.
     internal inner class AssignMultitenancyState {
 
         private lateinit var context: BoundedContext
@@ -267,12 +307,14 @@ internal class BoundedContextSpec {
             context = multiTenant()
             assertMultitenancyEqual(
                 { context.isMultitenant },
-                { context.commandBus().isMultitenant })
+                { context.commandBus().isMultitenant }
+            )
 
             context = singleTenant()
             assertMultitenancyEqual(
                 { context.isMultitenant },
-                { context.commandBus().isMultitenant })
+                { context.commandBus().isMultitenant }
+            )
         }
 
         @Test
@@ -281,13 +323,15 @@ internal class BoundedContextSpec {
 
             assertMultitenancyEqual(
                 { context.isMultitenant },
-                { context.stand().isMultitenant })
+                { context.stand().isMultitenant }
+            )
 
             context = singleTenant()
 
             assertMultitenancyEqual(
                 { context.isMultitenant },
-                { context.stand().isMultitenant })
+                { context.stand().isMultitenant }
+            )
         }
 
         private fun assertMultitenancyEqual(s1: BooleanSupplier, s2: BooleanSupplier) {
@@ -295,24 +339,24 @@ internal class BoundedContextSpec {
         }
 
         private fun multiTenant(): BoundedContext =
-            BoundedContextBuilder.assumingTests(true).build()
+            assumingTests(true).build()
 
         private fun singleTenant(): BoundedContext =
-            BoundedContextBuilder.assumingTests(false).build()
+            assumingTests(false).build()
     }
 
     /**
      * Simply checks that the result isn't empty to cover the integration with
      * [VisibilityGuard].
      *
-     * See [tests of VisibilityGuard][io.spine.server.entity.VisibilityGuardTest]
+     * See [tests of VisibilityGuard][io.spine.server.VisibilityGuard]
      * for how visibility filtering works.
      */
     @Test
     fun `obtain entity types by visibility`() {
-        context.stateTypes(EntityOption.Visibility.FULL).shouldBeEmpty()
+        context.stateTypes(FULL).shouldBeEmpty()
         registerAll()
-        context.stateTypes(EntityOption.Visibility.FULL).shouldNotBeEmpty()
+        context.stateTypes(FULL).shouldNotBeEmpty()
     }
 
     @Test
@@ -334,7 +378,7 @@ internal class BoundedContextSpec {
     @DisplayName("prohibit 3rd-party descendants")
     fun `prohibit 3rd-party descendants`() {
         assertThrows<IllegalStateException> {
-            object : BoundedContext(BoundedContextBuilder.assumingTests()) {
+            object : BoundedContext(assumingTests()) {
                 @Internal
                 override fun systemClient(): SystemClient = TestValues.nullRef()
             }
@@ -395,7 +439,6 @@ internal class BoundedContextSpec {
 
     @Nested
     @DisplayName("do not allow registration calls from outside the `io.spine.server` package for")
-    @Suppress("TestFunctionName") // For readability of methods named after class names.
     internal inner class RestrictRegistrationCalls {
 
         @Test
@@ -424,11 +467,16 @@ internal class BoundedContextSpec {
         val c2 = BoundedContext.singleTenant("Two").build()
         val c1m = BoundedContext.multitenant("One").build()
         val c2m = BoundedContext.multitenant("Two").build()
-
-        EqualsTester()
-            .addEqualityGroup(c1, c1m)
-            .addEqualityGroup(c2, c2m)
-            .testEquals()
+        try {
+            EqualsTester()
+                .addEqualityGroup(c1, c1m)
+                .addEqualityGroup(c2, c2m)
+                .testEquals()
+        } finally {
+            listOf(c1, c2, c1m, c2m).forEach {
+                it.close()
+            }
+        }
     }
 
     @Test
@@ -436,9 +484,71 @@ internal class BoundedContextSpec {
         val c1 = BoundedContext.singleTenant("1").build()
         val c2 = BoundedContext.singleTenant("2").build()
 
-        assertThat(c1).isLessThan(c2)
-        assertThat(c2).isGreaterThan(c1)
-        assertThat(c1).isEqualTo(BoundedContext.multitenant("1").build())
+        try {
+            assertThat(c1).isLessThan(c2)
+            assertThat(c2).isGreaterThan(c1)
+            assertThat(c1).isEqualTo(BoundedContext.multitenant("1").build())
+        } finally {
+            listOf(c1, c2).forEach {
+                it.close()
+            }
+        }
+    }
+
+    @Nested
+    @DisplayName("support `Probe`")
+    inner class SupportProbe {
+
+        private val probe: BoundedContext.Probe = EmptyProbe()
+
+        @BeforeEach
+        fun installProbe() {
+            context.install(probe)
+        }
+
+        @AfterEach
+        fun removeProbe() {
+            if (context.hasProbe()) {
+                context.removeProbe()
+            }
+        }
+
+        @Test
+        fun installation() {
+            context.hasProbe() shouldBe true
+        }
+
+        @Test
+        fun removal() {
+            context.hasProbe() shouldBe true
+            context.removeProbe()
+            context.hasProbe() shouldBe false
+        }
+
+        @Test
+        fun `allowing passing the same instance`() {
+            assertDoesNotThrow {
+                context.install(probe)
+            }
+        }
+
+        @Test
+        fun `removal when the context closes`() {
+            context.close()
+            context.hasProbe() shouldBe false
+        }
+    }
+
+    @Test
+    fun `call 'onBeforeClose' when configured`() {
+        var called = false
+        val context = assumingTests()
+            .setOnBeforeClose { called = true }
+            .build()
+        context.use {
+            it.close()
+        }
+        called shouldBe true
     }
 
     companion object {
@@ -487,3 +597,14 @@ internal class BoundedContextSpec {
         }
     }
 }
+
+private class EmptyProbe : BoundedContext.Probe {
+    private lateinit var context: BoundedContext
+    override fun registerWith(context: BoundedContext) {
+        this.context = context
+    }
+    override fun isRegistered(): Boolean = this::context.isInitialized
+    override fun commandListener(): Listener<CommandEnvelope> = Listener<CommandEnvelope> { _ -> }
+    override fun eventListener(): Listener<EventEnvelope> = Listener<EventEnvelope> { _ -> }
+    override fun eventDispatchers(): Set<EventDispatcher> = mutableSetOf()
+}

From e97f29f42be366247a210b1f638c78d97b011930 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 22:04:19 +0000
Subject: [PATCH 11/32] Add `BoundedContext` tests

Also:
  * Fix an error message in `Policy`.
---
 .../java/io/spine/server/BoundedContext.java  |  3 +-
 .../kotlin/io/spine/server/event/Policy.kt    |  7 +-
 .../test/java/com/example/ForeignClass.java   |  5 ++
 .../io/spine/server/BoundedContextSpec.kt     | 85 ++++++++++++++-----
 .../test/proto/spine/test/shared_events.proto | 51 +++++++++++
 5 files changed, 124 insertions(+), 27 deletions(-)
 create mode 100644 server/src/test/proto/spine/test/shared_events.proto

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 4f900bde252..42b3e7efb06 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -524,8 +524,7 @@ private void shutDownRepositories() {
      */
     @Override
     public String toString() {
-        return spec.name()
-                   .getValue();
+        return spec.name().value();
     }
 
     /**
diff --git a/server/src/main/kotlin/io/spine/server/event/Policy.kt b/server/src/main/kotlin/io/spine/server/event/Policy.kt
index 61128bd4bc7..ff406c6b77d 100644
--- a/server/src/main/kotlin/io/spine/server/event/Policy.kt
+++ b/server/src/main/kotlin/io/spine/server/event/Policy.kt
@@ -33,6 +33,7 @@ import io.spine.core.ContractFor
 import io.spine.logging.WithLogging
 import io.spine.server.BoundedContext
 import io.spine.server.type.EventClass
+import io.spine.string.Diags
 
 /**
  * A policy converts one event into zero to many other events.
@@ -63,7 +64,7 @@ public abstract class Policy<E : EventMessage> : AbstractEventReactor(), WithLog
      * Handles an event and produces some number of events in response.
      */
     @ContractFor(handler = React::class)
-    protected abstract fun whenever(event: E): Iterable<Message>
+    protected abstract fun whenever(event: E): Iterable<EventMessage>
 
     final override fun registerWith(context: BoundedContext) {
         super.registerWith(context)
@@ -85,7 +86,9 @@ public abstract class Policy<E : EventMessage> : AbstractEventReactor(), WithLog
     private fun checkReceptors(events: Iterable<EventClass>) {
         val classes = events.toList()
         check(classes.size == 1) {
-            "Policy `${javaClass.name}` handles too many events: [${classes.joinToString()}]."
+            "A policy should handle only one event." +
+                    " `${javaClass.name}` attempts to handle ${classes.size}:" +
+                    " [${classes.stream().collect(Diags.toEnumerationBackticked())}]."
         }
     }
 }
diff --git a/server/src/test/java/com/example/ForeignClass.java b/server/src/test/java/com/example/ForeignClass.java
index 3d0ab22957b..e2b428a23b2 100644
--- a/server/src/test/java/com/example/ForeignClass.java
+++ b/server/src/test/java/com/example/ForeignClass.java
@@ -26,6 +26,7 @@
 
 package com.example;
 
+import io.spine.server.BoundedContext;
 import io.spine.server.security.GivenRestrictedApi;
 import io.spine.server.security.Security;
 
@@ -42,4 +43,8 @@ private ForeignClass() {}
     public static void attemptToCallRestrictedApi() {
         GivenRestrictedApi.guardedMethod();
     }
+
+    public static void callInternalOf(BoundedContext context) {
+        context.internalAccess();
+    }
 }
diff --git a/server/src/test/java/io/spine/server/BoundedContextSpec.kt b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
index 17520d4cea6..14db370a5f7 100644
--- a/server/src/test/java/io/spine/server/BoundedContextSpec.kt
+++ b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
@@ -25,24 +25,32 @@
  */
 package io.spine.server
 
+import com.example.ForeignClass
 import com.example.ForeignContextConfig
 import com.google.common.collect.ImmutableSet
 import com.google.common.collect.Sets
 import com.google.common.testing.EqualsTester
-import com.google.common.truth.Truth.assertThat
+import com.google.protobuf.Message
 import io.kotest.matchers.collections.shouldBeEmpty
 import io.kotest.matchers.collections.shouldContain
 import io.kotest.matchers.collections.shouldNotBeEmpty
 import io.kotest.matchers.collections.shouldNotContain
+import io.kotest.matchers.comparables.shouldBeGreaterThan
+import io.kotest.matchers.comparables.shouldBeLessThan
 import io.kotest.matchers.optional.shouldBeEmpty
+import io.kotest.matchers.optional.shouldBePresent
+import io.kotest.matchers.optional.shouldNotBeEmpty
 import io.kotest.matchers.shouldBe
 import io.kotest.matchers.shouldNotBe
 import io.spine.annotation.Internal
+import io.spine.base.EventMessage
 import io.spine.core.BoundedContextName
 import io.spine.core.BoundedContextNames
 import io.spine.logging.Level.Companion.DEBUG
 import io.spine.logging.toJavaLogging
 import io.spine.option.EntityOption.Visibility.FULL
+import io.spine.server.BoundedContext.multitenant
+import io.spine.server.BoundedContext.singleTenant
 import io.spine.server.BoundedContextBuilder.assumingTests
 import io.spine.server.bc.given.AnotherProjectAggregate
 import io.spine.server.bc.given.FinishedProjectProjection
@@ -58,17 +66,20 @@ import io.spine.server.bus.Listener
 import io.spine.server.entity.Entity
 import io.spine.server.entity.Repository
 import io.spine.server.event.EventDispatcher
+import io.spine.server.event.Policy
+import io.spine.server.event.React
 import io.spine.server.type.CommandEnvelope
 import io.spine.server.type.EventEnvelope
 import io.spine.system.server.SystemClient
 import io.spine.system.server.SystemContext
 import io.spine.test.bc.Project
 import io.spine.test.bc.SecretProject
+import io.spine.test.shared.event.SomethingElseHappened
+import io.spine.test.shared.event.SomethingHappened
 import io.spine.testing.TestValues
 import io.spine.testing.logging.Interceptor
 import io.spine.testing.server.model.ModelTests
 import java.util.function.BooleanSupplier
-import java.util.function.Consumer
 import java.util.logging.Level
 import java.util.stream.Stream
 import org.junit.jupiter.api.AfterEach
@@ -96,10 +107,11 @@ import org.junit.jupiter.params.provider.MethodSource
 @DisplayName("`BoundedContext` should")
 @Suppress("TestFunctionName") // For readability of methods named after class names.
 internal class BoundedContextSpec {
-    private val subscriber = TestEventSubscriber()
 
     private lateinit var context: BoundedContext
 
+    private val subscriber = TestEventSubscriber()
+
     private var handlersRegistered = false
 
     @BeforeEach
@@ -162,27 +174,31 @@ internal class BoundedContextSpec {
         }
     }
 
-
     @Nested
     @DisplayName("provide internal secured access to")
     inner class InternalAccess {
 
-        private val internalAccess = context.internalAccess()
+        private lateinit var access: BoundedContext.InternalAccess
+
+        @BeforeEach
+        fun getAccess() {
+            access = context.internalAccess()
+        }
 
         @Test
         fun IntegrationBroker() {
-            internalAccess.broker() shouldNotBe null
+            access.broker() shouldNotBe null
         }
 
         @Test
         fun TenantIndex() {
-            internalAccess.tenantIndex() shouldNotBe null
+            access.tenantIndex() shouldNotBe null
         }
 
         @Test
         fun `prohibiting access from outside of the 'server' package`() {
             assertThrows<SecurityException> {
-                Consumer<Any> { context.internalAccess() }
+                ForeignClass.callInternalOf(context)
             }
         }
     }
@@ -397,7 +413,7 @@ internal class BoundedContextSpec {
 
         @BeforeEach
         fun closeContext() {
-            val context = BoundedContext.singleTenant(contextName.value).build()
+            val context = singleTenant(contextName.value).build()
             domainInterceptor = Interceptor(DomainContext::class.java, debugLevel)
             domainInterceptor.intercept()
             systemInterceptor = Interceptor(SystemContext::class.java, debugLevel)
@@ -432,7 +448,7 @@ internal class BoundedContextSpec {
     @Test
     fun `return its name in 'toString()'`() {
         val name = TestValues.randomString()
-        BoundedContext.singleTenant(name).build().use {
+        singleTenant(name).build().use {
             it.toString() shouldBe name
         }
     }
@@ -463,10 +479,10 @@ internal class BoundedContextSpec {
 
     @Test
     fun `be equal to another context by its name`() {
-        val c1 = BoundedContext.singleTenant("One").build()
-        val c2 = BoundedContext.singleTenant("Two").build()
-        val c1m = BoundedContext.multitenant("One").build()
-        val c2m = BoundedContext.multitenant("Two").build()
+        val c1 = singleTenant("One").build()
+        val c2 = singleTenant("Two").build()
+        val c1m = multitenant("One").build()
+        val c2m = multitenant("Two").build()
         try {
             EqualsTester()
                 .addEqualityGroup(c1, c1m)
@@ -481,13 +497,14 @@ internal class BoundedContextSpec {
 
     @Test
     fun `be comparable by its name`() {
-        val c1 = BoundedContext.singleTenant("1").build()
-        val c2 = BoundedContext.singleTenant("2").build()
-
+        val c1 = singleTenant("1").build()
+        val c2 = singleTenant("2").build()
         try {
-            assertThat(c1).isLessThan(c2)
-            assertThat(c2).isGreaterThan(c1)
-            assertThat(c1).isEqualTo(BoundedContext.multitenant("1").build())
+            c1 shouldBeLessThan c2
+            c2 shouldBeGreaterThan c1
+            multitenant("1").build().use {
+                c1 shouldBe it
+            }
         } finally {
             listOf(c1, c2).forEach {
                 it.close()
@@ -496,7 +513,7 @@ internal class BoundedContextSpec {
     }
 
     @Nested
-    @DisplayName("support `Probe`")
+    @DisplayName("support diagnostics via `Probe`")
     inner class SupportProbe {
 
         private val probe: BoundedContext.Probe = EmptyProbe()
@@ -516,6 +533,9 @@ internal class BoundedContextSpec {
         @Test
         fun installation() {
             context.hasProbe() shouldBe true
+            context.probe().shouldBePresent {
+                it shouldBe probe
+            }
         }
 
         @Test
@@ -526,12 +546,19 @@ internal class BoundedContextSpec {
         }
 
         @Test
-        fun `allowing passing the same instance`() {
+        fun `allowing passing the same probe`() {
             assertDoesNotThrow {
                 context.install(probe)
             }
         }
 
+        @Test
+        fun `prohibiting setting another probe`() {
+            assertThrows<IllegalStateException> {
+                context.install(EmptyProbe())
+            }
+        }
+
         @Test
         fun `removal when the context closes`() {
             context.close()
@@ -606,5 +633,17 @@ private class EmptyProbe : BoundedContext.Probe {
     override fun isRegistered(): Boolean = this::context.isInitialized
     override fun commandListener(): Listener<CommandEnvelope> = Listener<CommandEnvelope> { _ -> }
     override fun eventListener(): Listener<EventEnvelope> = Listener<EventEnvelope> { _ -> }
-    override fun eventDispatchers(): Set<EventDispatcher> = mutableSetOf()
+    override fun eventDispatchers(): Set<EventDispatcher> = mutableSetOf(
+            StubPolicy1(), StubPolicy2()
+        )
+}
+
+private class StubPolicy1: Policy<SomethingHappened>() {
+    @React
+    override fun whenever(event: SomethingHappened): Iterable<EventMessage> = setOf()
+}
+
+private class StubPolicy2: Policy<SomethingElseHappened>() {
+    @React
+    override fun whenever(event: SomethingElseHappened): Iterable<EventMessage> = setOf()
 }
diff --git a/server/src/test/proto/spine/test/shared_events.proto b/server/src/test/proto/spine/test/shared_events.proto
new file mode 100644
index 00000000000..7bf02f3e5eb
--- /dev/null
+++ b/server/src/test/proto/spine/test/shared_events.proto
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2022, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+syntax = "proto3";
+
+package spine.test.event;
+
+import "spine/options.proto";
+
+option (type_url_prefix) = "type.spine.io";
+option java_package = "io.spine.test.shared.event";
+option java_outer_classname = "SharedEventsProto";
+option java_multiple_files = true;
+
+/**
+ * This is a stub event message for the cases when we need just a valid event message and
+ * are not interested in its contents.
+ */
+message SomethingHappened {
+    string description = 1;
+}
+
+/**
+ * Similar to `SomethingHappened` but with a different type for cases when more than one
+ * stub event is required.
+ */
+message SomethingElseHappened {
+    string description = 1;
+}

From 458d589fbbdac1d10bcfad508e47dcf872756398 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 22:56:42 +0000
Subject: [PATCH 12/32] Test with a policy handling external event

---
 .../java/io/spine/server/BoundedContextSpec.kt    | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/server/src/test/java/io/spine/server/BoundedContextSpec.kt b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
index 14db370a5f7..e18f52bf225 100644
--- a/server/src/test/java/io/spine/server/BoundedContextSpec.kt
+++ b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
@@ -30,7 +30,6 @@ import com.example.ForeignContextConfig
 import com.google.common.collect.ImmutableSet
 import com.google.common.collect.Sets
 import com.google.common.testing.EqualsTester
-import com.google.protobuf.Message
 import io.kotest.matchers.collections.shouldBeEmpty
 import io.kotest.matchers.collections.shouldContain
 import io.kotest.matchers.collections.shouldNotBeEmpty
@@ -39,13 +38,13 @@ import io.kotest.matchers.comparables.shouldBeGreaterThan
 import io.kotest.matchers.comparables.shouldBeLessThan
 import io.kotest.matchers.optional.shouldBeEmpty
 import io.kotest.matchers.optional.shouldBePresent
-import io.kotest.matchers.optional.shouldNotBeEmpty
 import io.kotest.matchers.shouldBe
 import io.kotest.matchers.shouldNotBe
 import io.spine.annotation.Internal
 import io.spine.base.EventMessage
 import io.spine.core.BoundedContextName
 import io.spine.core.BoundedContextNames
+import io.spine.core.External
 import io.spine.logging.Level.Companion.DEBUG
 import io.spine.logging.toJavaLogging
 import io.spine.option.EntityOption.Visibility.FULL
@@ -70,6 +69,7 @@ import io.spine.server.event.Policy
 import io.spine.server.event.React
 import io.spine.server.type.CommandEnvelope
 import io.spine.server.type.EventEnvelope
+import io.spine.system.server.ConstraintViolated
 import io.spine.system.server.SystemClient
 import io.spine.system.server.SystemContext
 import io.spine.test.bc.Project
@@ -634,7 +634,7 @@ private class EmptyProbe : BoundedContext.Probe {
     override fun commandListener(): Listener<CommandEnvelope> = Listener<CommandEnvelope> { _ -> }
     override fun eventListener(): Listener<EventEnvelope> = Listener<EventEnvelope> { _ -> }
     override fun eventDispatchers(): Set<EventDispatcher> = mutableSetOf(
-            StubPolicy1(), StubPolicy2()
+            StubPolicy1(), StubPolicy2(), StubPolicy3()
         )
 }
 
@@ -647,3 +647,12 @@ private class StubPolicy2: Policy<SomethingElseHappened>() {
     @React
     override fun whenever(event: SomethingElseHappened): Iterable<EventMessage> = setOf()
 }
+
+/**
+ * A policy which reacts to an external event.
+ */
+private class StubPolicy3: Policy<ConstraintViolated>() {
+    @React
+    override fun whenever(@External event: ConstraintViolated): Iterable<EventMessage> = setOf()
+
+}

From 26be6bf9d2bb0b2c78f98cd6eab09f91eca81c88 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 22:56:55 +0000
Subject: [PATCH 13/32] Improve documentation layout

---
 .../java/io/spine/server/BoundedContext.java  | 21 ++++++++++++----
 .../aggregate/AggregateRootDirectory.java     | 15 ++++++------
 .../commandbus/CommandDispatcherRegistry.java | 24 +++++++++++--------
 .../io/spine/server/BoundedContextExts.kt     |  6 +++++
 .../kotlin/io/spine/server/event/Policy.kt    |  1 -
 5 files changed, 45 insertions(+), 22 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 42b3e7efb06..ce7021cb3e7 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -134,7 +134,7 @@ public abstract class BoundedContext
      * Creates new instance.
      *
      * @throws IllegalStateException
-     *         if called from a derived class, which is not a part of the framework
+     *          if called from a derived class, which is not a part of the framework
      * @apiNote
      * This constructor is for internal use of the framework. Application developers should not
      * create classes derived from {@code BoundedContext}.
@@ -277,11 +277,12 @@ private void unregisterCommandDispatcher(CommandDispatcherDelegate dispatcher) {
     /**
      * Registering the passed event dispatcher with the buses of this context.
      *
-     * <p>If the passed instance dispatches domestic events, registers it with the {@code EventBus}.
-     * If the passed instance dispatches external events, registers it with
+     * <p>If the given instance dispatches domestic events, registers it with the {@code EventBus}.
+     * If the given instance dispatches external events, registers it with
      * the {@code IntegrationBroker}.
      *
      * @see #registerEventDispatcher(EventDispatcherDelegate)
+     * @see #unregisterEventDispatcher(EventDispatcher)
      */
     protected void registerEventDispatcher(EventDispatcher dispatcher) {
         checkNotNull(dispatcher);
@@ -302,7 +303,16 @@ protected void registerEventDispatcher(EventDispatcher dispatcher) {
         }
     }
 
-    protected void unregisterEventDispatcher(EventDispatcher dispatcher) {
+    /**
+     * Unregisters the passed event dispatcher from the buses of this context.
+     *
+     * <p>If the given instance dispatches domestic events, unregisters it from
+     * the {@code EventBus}. If the given instance dispatches external events, unregisters it from
+     * the {@code IntegrationBroker}.
+     *
+     * @see #registerEventDispatcher(EventDispatcher)
+     */
+    private void unregisterEventDispatcher(EventDispatcher dispatcher) {
         checkNotNull(dispatcher);
         Security.allowOnlyFrameworkServer();
         unregisterIfAware(dispatcher);
@@ -748,6 +758,9 @@ public TenantIndex tenantIndex() {
             return tenantIndex;
         }
 
+        /**
+         * Obtains an {@link AggregateRootDirectory} of this {@code BoundedContext}.
+         */
         public AggregateRootDirectory aggregateRootDirectory() {
             return aggregateRootDirectory;
         }
diff --git a/server/src/main/java/io/spine/server/aggregate/AggregateRootDirectory.java b/server/src/main/java/io/spine/server/aggregate/AggregateRootDirectory.java
index ac130afd411..20ff7ac4bb4 100644
--- a/server/src/main/java/io/spine/server/aggregate/AggregateRootDirectory.java
+++ b/server/src/main/java/io/spine/server/aggregate/AggregateRootDirectory.java
@@ -35,8 +35,8 @@
 /**
  * A mapping of aggregate roots to the associated {@linkplain AggregatePart parts}.
  *
- * <p>In the directory, the aggregate root is represented by its type and the parts - by their
- * repositories.
+ * <p>In the directory, the aggregate root is represented by its type and
+ * the parts - by their repositories.
  */
 @Experimental
 @SPI
@@ -48,17 +48,18 @@ public interface AggregateRootDirectory {
     void register(AggregatePartRepository<?, ?, ?, ?> repository);
 
     /**
-     * Looks up an aggregate part repository by the type of the root and the type of the part state.
+     * Looks up an aggregate part repository by the type of the root and
+     * the type of the part state.
      *
-     * <p>If a matching repository if registered, it is obtained by this method with no regard to
-     * the visibility of the aggregate.
+     * <p>If a matching repository if registered, it is obtained by this method with
+     * no regard to the visibility of the aggregate.
      *
      * @param rootClass
      *         the type of the aggregate root
      * @param partStateClass
      *         the type of the part state
-     * @return the {@link AggregatePartRepository} or {@code Optional.empty()} if such a repository
-     *         is not registered
+     * @return the {@link AggregatePartRepository} or {@code Optional.empty()} if
+     *         such a repository is not registered
      */
     Optional<? extends AggregatePartRepository<?, ?, ?, ?>>
     findPart(Class<? extends AggregateRoot<?>> rootClass,
diff --git a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
index 04a518cfd94..928f1868015 100644
--- a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
+++ b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherRegistry.java
@@ -72,9 +72,11 @@ public void register(CommandDispatcher dispatcher) {
      * <p>Ensures that there are not dispatchers already registered for
      * the commands of this dispatcher.
      *
-     * @param dispatcher the dispatcher to check
-     * @throws IllegalStateException if there is at least one command of the passed dispatcher
-     *                               that already has a registered dispatcher
+     * @param dispatcher
+     *         the dispatcher to check
+     * @throws IllegalStateException
+     *          if there is at least one command of the passed dispatcher that already
+     *          has a registered dispatcher
      */
     @Override
     protected void checkDispatcher(CommandDispatcher dispatcher)
@@ -87,8 +89,8 @@ protected void checkDispatcher(CommandDispatcher dispatcher)
      * Ensures that all of the commands of the passed dispatcher are not
      * already registered for dispatched in this command bus.
      *
-     * @throws IllegalArgumentException if at least one command class already has
-     *                                  a registered dispatcher
+     * @throws IllegalArgumentException
+     *          if at least one command class already has a registered dispatcher
      */
     private void checkNotAlreadyRegistered(CommandDispatcher dispatcher) {
         Set<CommandClass> commandClasses = dispatcher.messageClasses();
@@ -107,9 +109,12 @@ private void checkNotAlreadyRegistered(CommandDispatcher dispatcher) {
      *
      * <p>This is a convenience method for checking registration of handling dispatching.
      *
-     * @param alreadyRegistered the map of already registered classes or an empty set
-     * @param registeringObject the object which tries to register dispatching or handling
-     * @throws IllegalArgumentException if the set is not empty
+     * @param alreadyRegistered
+     *         the map of already registered classes or an empty set
+     * @param registeringObject
+     *         the object which tries to register dispatching or handling
+     * @throws IllegalArgumentException
+     *         if the set is not empty
      */
     private static void doCheck(Map<CommandClass, CommandDispatcher> alreadyRegistered,
                                 Object registeringObject) {
@@ -136,8 +141,7 @@ protected Set<CommandClass> registeredMessageClasses() {
     /**
      * {@inheritDoc}
      *
-     * <p>Overrides to expose the method to
-     * {@link CommandBus#close() CommandBus}.
+     * <p>Overrides to expose the method to {@link CommandBus#close() CommandBus}.
      */
     @Override
     protected void unregisterAll() {
diff --git a/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt b/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
index a412fc12bad..417132e8b4d 100644
--- a/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
+++ b/server/src/main/kotlin/io/spine/server/BoundedContextExts.kt
@@ -29,8 +29,14 @@ package io.spine.server
 import io.spine.base.EntityState
 import io.spine.server.entity.Entity
 
+/**
+ * Tells if the bounded context has entities of the given type.
+ */
 public inline fun <reified E: Entity<*, *>> BoundedContext.hasEntitiesOfType(): Boolean =
     hasEntitiesOfType(E::class.java)
 
+/**
+ * Tells if the bounded context has entities with the given state type.
+ */
 public inline fun <reified S: EntityState<*>> BoundedContext.hasEntitiesWithState(): Boolean =
     hasEntitiesWithState(S::class.java)
diff --git a/server/src/main/kotlin/io/spine/server/event/Policy.kt b/server/src/main/kotlin/io/spine/server/event/Policy.kt
index ff406c6b77d..e2fdc9b270f 100644
--- a/server/src/main/kotlin/io/spine/server/event/Policy.kt
+++ b/server/src/main/kotlin/io/spine/server/event/Policy.kt
@@ -27,7 +27,6 @@
 package io.spine.server.event
 
 import com.google.common.collect.ImmutableSet
-import com.google.protobuf.Message
 import io.spine.base.EventMessage
 import io.spine.core.ContractFor
 import io.spine.logging.WithLogging

From c54a9e569e217976e6443a4ddeb7633f1a66b0bf Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 23:42:12 +0000
Subject: [PATCH 14/32] Use Kotlin ext. fun

---
 server/src/main/kotlin/io/spine/server/event/Policy.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/server/src/main/kotlin/io/spine/server/event/Policy.kt b/server/src/main/kotlin/io/spine/server/event/Policy.kt
index e2fdc9b270f..e5e61ee0b17 100644
--- a/server/src/main/kotlin/io/spine/server/event/Policy.kt
+++ b/server/src/main/kotlin/io/spine/server/event/Policy.kt
@@ -87,7 +87,7 @@ public abstract class Policy<E : EventMessage> : AbstractEventReactor(), WithLog
         check(classes.size == 1) {
             "A policy should handle only one event." +
                     " `${javaClass.name}` attempts to handle ${classes.size}:" +
-                    " [${classes.stream().collect(Diags.toEnumerationBackticked())}]."
+                    " [${classes.joinToString(separator = "`, `", prefix = "`", postfix = "`")}]."
         }
     }
 }

From 15c48214598d8271f8fa8129a4116f58014a5bdc Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 23:42:33 +0000
Subject: [PATCH 15/32] Bump external dependencies

---
 .../io/spine/internal/dependency/Guava.kt     |   2 +-
 .../io/spine/internal/dependency/Jackson.kt   |   4 +-
 .../io/spine/internal/dependency/Protobuf.kt  |   2 +-
 license-report.md                             | 210 +++++++++---------
 4 files changed, 103 insertions(+), 115 deletions(-)

diff --git a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Guava.kt b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Guava.kt
index c99f17fa707..810a8041558 100644
--- a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Guava.kt
+++ b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Guava.kt
@@ -37,7 +37,7 @@ package io.spine.internal.dependency
  */
 @Suppress("unused", "ConstPropertyName")
 object Guava {
-    private const val version = "32.1.2-jre"
+    private const val version = "32.1.3-jre"
     const val lib     = "com.google.guava:guava:${version}"
     const val testLib = "com.google.guava:guava-testlib:${version}"
 }
diff --git a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Jackson.kt b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Jackson.kt
index 3b2821668bc..8bfaa5c1b26 100644
--- a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Jackson.kt
+++ b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Jackson.kt
@@ -29,8 +29,8 @@ package io.spine.internal.dependency
 // https://github.com/FasterXML/jackson/wiki/Jackson-Releases
 @Suppress("unused", "ConstPropertyName")
 object Jackson {
-    const val version = "2.15.2"
-    private const val databindVersion = "2.15.2"
+    const val version = "2.15.3"
+    private const val databindVersion = "2.15.3"
 
     private const val coreGroup = "com.fasterxml.jackson.core"
     private const val dataformatGroup = "com.fasterxml.jackson.dataformat"
diff --git a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Protobuf.kt b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Protobuf.kt
index c115f9b4224..8f02b9b6a3d 100644
--- a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Protobuf.kt
+++ b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Protobuf.kt
@@ -33,7 +33,7 @@ package io.spine.internal.dependency
 )
 object Protobuf {
     private const val group = "com.google.protobuf"
-    const val version       = "3.24.1"
+    const val version       = "3.24.4"
     val libs = listOf(
         "${group}:protobuf-java:${version}",
         "${group}:protobuf-java-util:${version}",
diff --git a/license-report.md b/license-report.md
index 69df68ab262..1bf9e5116ad 100644
--- a/license-report.md
+++ b/license-report.md
@@ -27,11 +27,10 @@
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
@@ -39,15 +38,15 @@
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : io.grpc. **Name** : grpc-api. **Version** : 1.57.2.
@@ -129,27 +128,27 @@
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -231,12 +230,11 @@
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -250,15 +248,15 @@
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -800,7 +798,7 @@
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Tue Oct 31 23:41:13 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
@@ -824,11 +822,10 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
@@ -836,15 +833,15 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : io.spine.validation. **Name** : spine-validation-java-runtime. **Version** : 2.0.0-SNAPSHOT.109.**No license information found**
@@ -894,27 +891,27 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -996,12 +993,11 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -1015,15 +1011,15 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -1565,7 +1561,7 @@ This report was generated on **Sat Oct 28 16:50:16 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
@@ -1597,11 +1593,10 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
@@ -1609,15 +1604,15 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : io.grpc. **Name** : grpc-api. **Version** : 1.57.2.
@@ -1699,27 +1694,27 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -1805,12 +1800,11 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -1824,15 +1818,15 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -2378,7 +2372,7 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
@@ -2422,12 +2416,11 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -2437,15 +2430,15 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.truth. **Name** : truth. **Version** : 1.1.5.
@@ -2625,27 +2618,27 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -2727,12 +2720,11 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -2746,15 +2738,15 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -3311,7 +3303,7 @@ This report was generated on **Sat Oct 28 16:50:17 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
@@ -3355,12 +3347,11 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -3370,15 +3361,15 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.truth. **Name** : truth. **Version** : 1.1.5.
@@ -3558,27 +3549,27 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -3660,12 +3651,11 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -3679,15 +3669,15 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -4244,7 +4234,7 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Tue Oct 31 23:41:15 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
@@ -4288,12 +4278,11 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -4303,15 +4292,15 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.truth. **Name** : truth. **Version** : 1.1.5.
@@ -4491,27 +4480,27 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://jcommander.org](https://jcommander.org)
      * **License:** [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.2.**No license information found**
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson. **Name** : jackson-bom. **Version** : 2.15.3.**No license information found**
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-annotations. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-core. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-core](https://github.com/FasterXML/jackson-core)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.core. **Name** : jackson-databind. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson](https://github.com/FasterXML/jackson)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.dataformat. **Name** : jackson-dataformat-xml. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-dataformat-xml](https://github.com/FasterXML/jackson-dataformat-xml)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.2.
+1.  **Group** : com.fasterxml.jackson.module. **Name** : jackson-module-kotlin. **Version** : 2.15.3.
      * **Project URL:** [https://github.com/FasterXML/jackson-module-kotlin](https://github.com/FasterXML/jackson-module-kotlin)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
      * **License:** [The Apache Software License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.txt)
@@ -4593,12 +4582,11 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/guava/](https://github.com/google/guava/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava. **Version** : 32.1.3-jre.
      * **Project URL:** [https://github.com/google/guava](https://github.com/google/guava)
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.guava. **Name** : guava-parent. **Version** : 32.1.2-jre.**No license information found**
-1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.2-jre.
+1.  **Group** : com.google.guava. **Name** : guava-testlib. **Version** : 32.1.3-jre.
      * **License:** [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
 1.  **Group** : com.google.guava. **Name** : listenablefuture. **Version** : 9999.0-empty-to-avoid-conflict-with-guava.
@@ -4612,15 +4600,15 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
      * **Project URL:** [https://github.com/google/j2objc/](https://github.com/google/j2objc/)
      * **License:** [The Apache Software License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0.txt)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-java-util. **Version** : 3.24.4.
      * **Project URL:** [https://developers.google.com/protocol-buffers/](https://developers.google.com/protocol-buffers/)
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
-1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.1.
+1.  **Group** : com.google.protobuf. **Name** : protobuf-kotlin. **Version** : 3.24.4.
      * **License:** [BSD-3-Clause](https://opensource.org/licenses/BSD-3-Clause)
 
 1.  **Group** : com.google.protobuf. **Name** : protoc. **Version** : 3.24.1.
@@ -5225,4 +5213,4 @@ This report was generated on **Sat Oct 28 16:50:18 WEST 2023** using [Gradle-Lic
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Sat Oct 28 16:50:19 WEST 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
+This report was generated on **Tue Oct 31 23:41:15 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file

From db38004136b52332ee7924b6bc3e2a45ea9ad0d5 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Tue, 31 Oct 2023 23:43:05 +0000
Subject: [PATCH 16/32] Optimise imports

---
 server/src/main/kotlin/io/spine/server/event/Policy.kt | 1 -
 1 file changed, 1 deletion(-)

diff --git a/server/src/main/kotlin/io/spine/server/event/Policy.kt b/server/src/main/kotlin/io/spine/server/event/Policy.kt
index e5e61ee0b17..23c28b29318 100644
--- a/server/src/main/kotlin/io/spine/server/event/Policy.kt
+++ b/server/src/main/kotlin/io/spine/server/event/Policy.kt
@@ -32,7 +32,6 @@ import io.spine.core.ContractFor
 import io.spine.logging.WithLogging
 import io.spine.server.BoundedContext
 import io.spine.server.type.EventClass
-import io.spine.string.Diags
 
 /**
  * A policy converts one event into zero to many other events.

From 596a8177780c6be0d01549a04942b6a869cc8bb0 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 01:22:04 +0000
Subject: [PATCH 17/32] Simplify creating `BlackBox` instances

Also:
  * Avoid checked exception on `close()`.
---
 .../java/io/spine/server/BoundedContext.java  |   5 +-
 .../spine/server/BoundedContextBuilder.java   |   5 +-
 .../main/java/io/spine/server/Closeable.java  |   8 ++
 .../java/io/spine/server/DomainContext.java   |  13 +-
 .../io/spine/server/aggregate/ImportBus.java  |   3 +-
 .../main/java/io/spine/server/bus/Bus.java    |   5 +-
 .../java/io/spine/server/bus/BusFilter.java   |   2 +-
 .../java/io/spine/server/bus/FilterChain.java |   4 +-
 .../java/io/spine/server/event/EventBus.java  |   2 +-
 .../server/integration/ConfigExchange.java    |   2 +-
 .../server/integration/IntegrationBroker.java |   2 +-
 .../server/integration/ThirdPartyContext.java |   5 +-
 .../io/spine/server/stand/EventRegistry.java  |   3 +
 .../java/io/spine/server/stand/Stand.java     |   2 +-
 .../io/spine/server/transport/ChannelHub.java |   2 +-
 .../server/transport/MessageChannel.java      |   5 +-
 .../system/server/DefaultSystemClient.java    |   2 +-
 .../io/spine/system/server/SystemClient.java  |   5 +-
 .../server/ServerEnvironmentConfigTest.java   |   2 +-
 .../AggregateHistoryTruncationTest.java       |   6 +-
 .../aggregate/AggregateRepositoryTest.java    |  21 ++--
 .../aggregate/ApplyAllowImportTest.java       |   6 +-
 .../server/aggregate/EventImportTest.java     |   6 +-
 .../DispatchingQueueSynchronisationTest.java  |  57 +++++----
 .../io/spine/server/delivery/CatchUpTest.java | 113 +++++++++---------
 .../spine/server/delivery/DeliveryTest.java   |  49 ++++----
 .../io/spine/server/delivery/NastyClient.java |  59 +++++----
 .../server/delivery/given/CounterCatchUp.java |  21 ++--
 .../given/ReceptionFailureTestEnv.java        |   6 +-
 .../server/log/AbstractEntityLoggingTest.java |   5 +-
 .../mirror/given/MirrorMigrationTestEnv.java  |   6 +-
 .../handler/MessageInterfaceResultTest.java   |   6 +-
 .../procman/ProcessManagerRepositoryTest.java |   5 +-
 .../server/projection/StateRoutingTest.java   |  13 +-
 .../e2e/ProjectionEndToEndTest.java           |  53 ++++----
 .../stand/EntityQueryProcessorTest.java       |   5 +-
 .../system/server/ConstraintViolatedTest.java |  77 ++++++------
 .../testing/server/blackbox/BlackBox.java     |  99 ++++++++++++++-
 .../server/blackbox/ClientFactory.java        |   2 +-
 39 files changed, 364 insertions(+), 328 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index ce7021cb3e7..5b0b53f9d1b 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -474,12 +474,9 @@ public boolean isMultitenant() {
      *     <li>Closes all registered {@linkplain Repository repositories}.
      *     <li>Removes a {@link Probe}, if it was {@linkplain #install(Probe) installed}.
      * </ol>
-     *
-     * @throws Exception
-     *         caused by closing one of the components
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         var isOpen = isOpen();
         if (isOpen && onBeforeClose != null) {
             onBeforeClose.accept(this);
diff --git a/server/src/main/java/io/spine/server/BoundedContextBuilder.java b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
index e27a62a726f..8206b5fa7cc 100644
--- a/server/src/main/java/io/spine/server/BoundedContextBuilder.java
+++ b/server/src/main/java/io/spine/server/BoundedContextBuilder.java
@@ -139,9 +139,10 @@ private BoundedContextBuilder(ContextSpec spec, SystemSettings systemSettings) {
     @Internal
     @VisibleForTesting
     public static BoundedContextBuilder assumingTests(boolean multitenant) {
+        var name = assumingTestsValue();
         var spec = multitenant
-                   ? multitenant(assumingTestsValue())
-                   : singleTenant(assumingTestsValue());
+                   ? multitenant(name)
+                   : singleTenant(name);
         return new BoundedContextBuilder(spec);
     }
 
diff --git a/server/src/main/java/io/spine/server/Closeable.java b/server/src/main/java/io/spine/server/Closeable.java
index f47c8e868ac..0dfb73f1017 100644
--- a/server/src/main/java/io/spine/server/Closeable.java
+++ b/server/src/main/java/io/spine/server/Closeable.java
@@ -49,6 +49,14 @@ public interface Closeable extends AutoCloseable {
      */
     boolean isOpen();
 
+    /**
+     * {@inheritDoc}
+     *
+     * <p>Overrides to remove the checked exception from the signature.
+     */
+    @Override
+    void close();
+
     /**
      * Ensures that the object is {@linkplain #isOpen() open}.
      *
diff --git a/server/src/main/java/io/spine/server/DomainContext.java b/server/src/main/java/io/spine/server/DomainContext.java
index 5531813f4cb..e36de181096 100644
--- a/server/src/main/java/io/spine/server/DomainContext.java
+++ b/server/src/main/java/io/spine/server/DomainContext.java
@@ -40,11 +40,11 @@
  * <p>All the user interactions with the system (such as
  * {@linkplain BoundedContext#register(Repository) repository registration},
  * {@linkplain BoundedContext#commandBus() command posting},
- * {@linkplain BoundedContext#findRepository(Class) query processing}, etc.) happen through
- * an instance of this class.
+ * {@linkplain BoundedContext.InternalAccess#findRepository(Class) query processing}, etc.) happen
+ * through an instance of this class.
  *
  * <p>Each {@code DomainContext} has an associated
- * {@link io.spine.system.server.SystemContext SystemContext}, which manages the meta information
+ * {@link io.spine.system.server.SystemContext SystemContext}, which manages the meta-information
  * about entities of this Bounded Context.
  *
  * @see io.spine.system.server.SystemContext SystemContext
@@ -53,8 +53,7 @@ final class DomainContext extends BoundedContext {
 
     private final SystemClient system;
 
-    private DomainContext(BoundedContextBuilder builder,
-                          SystemClient system) {
+    private DomainContext(BoundedContextBuilder builder, SystemClient system) {
         super(builder);
         this.system = checkNotNull(system);
     }
@@ -77,11 +76,9 @@ public SystemClient systemClient() {
      * {@inheritDoc}
      *
      * <p>Closes the system context as well.
-     *
-     * @throws Exception if one of the context components throws an error when closing
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         super.close();
         system.closeSystemContext();
     }
diff --git a/server/src/main/java/io/spine/server/aggregate/ImportBus.java b/server/src/main/java/io/spine/server/aggregate/ImportBus.java
index 06b3703a869..07fb490080b 100644
--- a/server/src/main/java/io/spine/server/aggregate/ImportBus.java
+++ b/server/src/main/java/io/spine/server/aggregate/ImportBus.java
@@ -82,7 +82,7 @@
 public final class ImportBus
         extends UnicastBus<Event, EventEnvelope, EventClass, EventImportDispatcher<?>> {
 
-    private final ImportValidator validator = new ImportValidator();
+    private static final ImportValidator validator = new ImportValidator();
     private final DeadImportEventHandler deadImportEventHandler = new DeadImportEventHandler();
     private final TenantIndex tenantIndex;
 
@@ -164,7 +164,6 @@ public MessageUnhandled handle(EventEnvelope event) {
     private static final class Registry
             extends DispatcherRegistry<EventClass, EventEnvelope, EventImportDispatcher<?>> {
 
-        @SuppressWarnings("RedundantMethodOverride") // Overrides to open access to the method.
         @Override
         protected Optional<EventImportDispatcher<?>> dispatcherOf(EventEnvelope event) {
             return super.dispatcherOf(event);
diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 39179cd1171..389d56437ae 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -235,12 +235,9 @@ public final boolean isOpen() {
 
     /**
      * Closes the {@linkplain BusFilter filters} of this bus and unregisters all the dispatchers.
-     *
-     * @throws Exception if either filters or the {@linkplain DispatcherRegistry} throws
-     *         an exception
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         filterChain().close();
         registry.unregisterAll();
     }
diff --git a/server/src/main/java/io/spine/server/bus/BusFilter.java b/server/src/main/java/io/spine/server/bus/BusFilter.java
index 00b45338f75..21a84b6a64f 100644
--- a/server/src/main/java/io/spine/server/bus/BusFilter.java
+++ b/server/src/main/java/io/spine/server/bus/BusFilter.java
@@ -123,7 +123,7 @@ default Optional<Ack> reject(E envelope, Error cause) {
      * <p>By default, performs no action.
      */
     @Override
-    default void close() throws Exception {
+    default void close() {
         // NoOp by default.
     }
 }
diff --git a/server/src/main/java/io/spine/server/bus/FilterChain.java b/server/src/main/java/io/spine/server/bus/FilterChain.java
index b6f199129bf..97797a892ce 100644
--- a/server/src/main/java/io/spine/server/bus/FilterChain.java
+++ b/server/src/main/java/io/spine/server/bus/FilterChain.java
@@ -82,12 +82,10 @@ boolean contains(BusFilter<E> filter) {
      *
      * @throws IllegalStateException
      *         on a repetitive call
-     * @throws Exception
-     *         if a filter throws an {@link Exception}
      * @see #isOpen()
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         checkOpen();
         closed = true;
         for (BusFilter<?> filter : chain.reverse()) {
diff --git a/server/src/main/java/io/spine/server/event/EventBus.java b/server/src/main/java/io/spine/server/event/EventBus.java
index 39e0a868890..233d482a7b6 100644
--- a/server/src/main/java/io/spine/server/event/EventBus.java
+++ b/server/src/main/java/io/spine/server/event/EventBus.java
@@ -258,7 +258,7 @@ protected void store(Iterable<Event> events) {
     }
 
     @Override
-    public void close() throws Exception {
+    public void close() {
         super.close();
         eventStore().close();
     }
diff --git a/server/src/main/java/io/spine/server/integration/ConfigExchange.java b/server/src/main/java/io/spine/server/integration/ConfigExchange.java
index 10c7e8dad36..872d4a60237 100644
--- a/server/src/main/java/io/spine/server/integration/ConfigExchange.java
+++ b/server/src/main/java/io/spine/server/integration/ConfigExchange.java
@@ -120,7 +120,7 @@ private static ExternalEventType typeOfTransmittedEvents(ChannelId channel) {
      * Bounded Context.
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         observers.forEach(ObserveWantedEvents::close);
         notifyTypesChanged();
     }
diff --git a/server/src/main/java/io/spine/server/integration/IntegrationBroker.java b/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
index 634cacd49dc..b4a1d1ac3d2 100644
--- a/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
+++ b/server/src/main/java/io/spine/server/integration/IntegrationBroker.java
@@ -196,7 +196,7 @@ public void unregister(EventDispatcher dispatcher) {
      * Removes all subscriptions and closes all the underlying transport channels.
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         if (config != null) {
             config.close();
         }
diff --git a/server/src/main/java/io/spine/server/integration/ThirdPartyContext.java b/server/src/main/java/io/spine/server/integration/ThirdPartyContext.java
index cbc50a5534b..5db5c167daf 100644
--- a/server/src/main/java/io/spine/server/integration/ThirdPartyContext.java
+++ b/server/src/main/java/io/spine/server/integration/ThirdPartyContext.java
@@ -174,12 +174,9 @@ private void checkTenant(ActorContext actorContext, EventMessage event) {
      * Closes this Context and clean up underlying resources.
      *
      * <p>Attempts of emitting an event from a closed Context result in an exception.
-     *
-     * @throws Exception
-     *         if the underlying {@link BoundedContext} fails to close
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         context.close();
     }
 
diff --git a/server/src/main/java/io/spine/server/stand/EventRegistry.java b/server/src/main/java/io/spine/server/stand/EventRegistry.java
index d24a5c8f797..d391197326a 100644
--- a/server/src/main/java/io/spine/server/stand/EventRegistry.java
+++ b/server/src/main/java/io/spine/server/stand/EventRegistry.java
@@ -61,4 +61,7 @@ interface EventRegistry extends AutoCloseable {
      * Retrieves all stored event types as {@link EventClass} instances.
      */
     ImmutableSet<EventClass> eventClasses();
+
+    @Override
+    void close();
 }
diff --git a/server/src/main/java/io/spine/server/stand/Stand.java b/server/src/main/java/io/spine/server/stand/Stand.java
index 68573b4751c..293e2a89bdb 100644
--- a/server/src/main/java/io/spine/server/stand/Stand.java
+++ b/server/src/main/java/io/spine/server/stand/Stand.java
@@ -380,7 +380,7 @@ public boolean isOpen() {
      * Closes the {@code Stand} performing necessary cleanups.
      */
     @Override
-    public void close() throws Exception {
+    public void close() {
         typeRegistry.close();
         eventRegistry.close();
     }
diff --git a/server/src/main/java/io/spine/server/transport/ChannelHub.java b/server/src/main/java/io/spine/server/transport/ChannelHub.java
index c3fea4de5df..da12b2dbace 100644
--- a/server/src/main/java/io/spine/server/transport/ChannelHub.java
+++ b/server/src/main/java/io/spine/server/transport/ChannelHub.java
@@ -119,7 +119,7 @@ public boolean isOpen() {
     }
 
     @Override
-    public void close() throws Exception {
+    public void close() {
         for (var channel : channels.values()) {
             channel.close();
         }
diff --git a/server/src/main/java/io/spine/server/transport/MessageChannel.java b/server/src/main/java/io/spine/server/transport/MessageChannel.java
index 3b18002e9e4..ef80af072f5 100644
--- a/server/src/main/java/io/spine/server/transport/MessageChannel.java
+++ b/server/src/main/java/io/spine/server/transport/MessageChannel.java
@@ -40,7 +40,7 @@ public interface MessageChannel extends AutoCloseable {
     ChannelId id();
 
     /**
-     * Allows to understand whether this channel is stale and can be closed.
+     * Allows understanding whether this channel is stale and can be closed.
      *
      * @return {@code true} if the channel is stale, {@code false} otherwise
      */
@@ -68,4 +68,7 @@ static ChannelId channelIdFor(TypeUrl messageType) {
                 .build();
         return channelId;
     }
+
+    @Override
+    void close();
 }
diff --git a/server/src/main/java/io/spine/system/server/DefaultSystemClient.java b/server/src/main/java/io/spine/system/server/DefaultSystemClient.java
index 730838530ad..a30adedfd92 100644
--- a/server/src/main/java/io/spine/system/server/DefaultSystemClient.java
+++ b/server/src/main/java/io/spine/system/server/DefaultSystemClient.java
@@ -63,7 +63,7 @@ public SystemReadSide readSide() {
     }
 
     @Override
-    public void closeSystemContext() throws Exception {
+    public void closeSystemContext() {
         context.close();
     }
 
diff --git a/server/src/main/java/io/spine/system/server/SystemClient.java b/server/src/main/java/io/spine/system/server/SystemClient.java
index 068b5cdd8a9..abadd59588e 100644
--- a/server/src/main/java/io/spine/system/server/SystemClient.java
+++ b/server/src/main/java/io/spine/system/server/SystemClient.java
@@ -46,9 +46,6 @@ public interface SystemClient {
 
     /**
      * Closes the underlying system context.
-     *
-     * @throws Exception
-     *         if the context thrown an exception when closing
      */
-    void closeSystemContext() throws Exception;
+    void closeSystemContext();
 }
diff --git a/server/src/test/java/io/spine/server/ServerEnvironmentConfigTest.java b/server/src/test/java/io/spine/server/ServerEnvironmentConfigTest.java
index 7a70b9dcd93..0231e53fdc7 100644
--- a/server/src/test/java/io/spine/server/ServerEnvironmentConfigTest.java
+++ b/server/src/test/java/io/spine/server/ServerEnvironmentConfigTest.java
@@ -453,7 +453,7 @@ public boolean isOpen() {
         }
 
         @Override
-        public void close() throws Exception {
+        public void close() {
             delegate.close();
         }
     }
diff --git a/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java b/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
index ba0187ceca5..30308f4d6bd 100644
--- a/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/AggregateHistoryTruncationTest.java
@@ -33,7 +33,6 @@
 import com.google.protobuf.util.Durations;
 import io.spine.core.Event;
 import io.spine.core.Version;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.ContextSpec;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.aggregate.AggregateStorageTest.TestAggregate;
@@ -96,10 +95,7 @@ class VerifyIntegrity {
         @DisplayName("restore the `Aggregate` state properly")
         void restoreAggregateState() {
             var repo = new FibonacciRepository();
-            var context = BlackBox.from(
-                    BoundedContextBuilder.assumingTests()
-                                         .add(repo)
-            );
+            var context = BlackBox.singleTenantWith(repo);
             try (context) {
                 // Set the starting numbers.
                 var setStartingNumbers = SetStartingNumbers.newBuilder()
diff --git a/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java b/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
index 552213be4fb..91a821ae363 100644
--- a/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
@@ -33,7 +33,6 @@
 import io.spine.core.Ack;
 import io.spine.core.Event;
 import io.spine.core.Events;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.aggregate.given.repo.AnemicAggregateRepository;
 import io.spine.server.aggregate.given.repo.EventDiscardingAggregateRepository;
 import io.spine.server.aggregate.given.repo.FailingAggregateRepository;
@@ -504,10 +503,7 @@ class PostEventsToBus {
         @BeforeEach
         void createAnotherRepository() {
             resetRepository();
-            context = BlackBox.from(
-                    BoundedContextBuilder.assumingTests()
-                                         .add(repository())
-            );
+            context = BlackBox.singleTenantWith(repository());
         }
 
         @Test
@@ -573,15 +569,12 @@ void throughEventFilter() {
                     .setProjectId(parent)
                     .addChildProjectId(id)
                     .build();
-            var context = BlackBox.from(
-                    BoundedContextBuilder.assumingTests()
-                                         .add(new EventDiscardingAggregateRepository())
-            );
-            context.receivesCommands(create, start)
-                   .receivesEvent(archived);
-            context.assertEvents()
-                   .isEmpty();
-            context.close();
+            try (var context = BlackBox.singleTenantWith(new EventDiscardingAggregateRepository())) {
+                context.receivesCommands(create, start)
+                       .receivesEvent(archived);
+                context.assertEvents()
+                       .isEmpty();
+            }
         }
 
         private void assertEventVersions(int... expectedVersions) {
diff --git a/server/src/test/java/io/spine/server/aggregate/ApplyAllowImportTest.java b/server/src/test/java/io/spine/server/aggregate/ApplyAllowImportTest.java
index f6951043bc4..cbbe796576e 100644
--- a/server/src/test/java/io/spine/server/aggregate/ApplyAllowImportTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/ApplyAllowImportTest.java
@@ -26,7 +26,6 @@
 
 package io.spine.server.aggregate;
 
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.aggregate.given.importado.DotSpace;
 import io.spine.server.aggregate.given.importado.ObjectId;
 import io.spine.server.aggregate.given.importado.event.Moved;
@@ -54,10 +53,7 @@ class ApplyAllowImportTest {
 
     @BeforeEach
     void setUp() {
-        context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(new DotSpace())
-        );
+        context = BlackBox.singleTenantWith(new DotSpace());
     }
 
     @AfterEach
diff --git a/server/src/test/java/io/spine/server/aggregate/EventImportTest.java b/server/src/test/java/io/spine/server/aggregate/EventImportTest.java
index e42d5ee3345..54efc0cbf25 100644
--- a/server/src/test/java/io/spine/server/aggregate/EventImportTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/EventImportTest.java
@@ -27,7 +27,6 @@
 package io.spine.server.aggregate;
 
 import io.spine.base.EventMessage;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.aggregate.given.klasse.EngineAggregate;
 import io.spine.server.aggregate.given.klasse.EngineId;
 import io.spine.server.aggregate.given.klasse.EngineRepository;
@@ -59,10 +58,7 @@ class EventImportTest {
 
     void createRepository(boolean routeByFirstMessageField) {
         repository = new EngineRepository(routeByFirstMessageField);
-        context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(repository)
-        );
+        context = BlackBox.singleTenantWith(repository);
     }
 
     @AfterEach
diff --git a/server/src/test/java/io/spine/server/bus/DispatchingQueueSynchronisationTest.java b/server/src/test/java/io/spine/server/bus/DispatchingQueueSynchronisationTest.java
index 856afd4baec..3b21ec60ce2 100644
--- a/server/src/test/java/io/spine/server/bus/DispatchingQueueSynchronisationTest.java
+++ b/server/src/test/java/io/spine/server/bus/DispatchingQueueSynchronisationTest.java
@@ -26,7 +26,6 @@
 
 package io.spine.server.bus;
 
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.bus.given.stock.JowDonsIndex;
 import io.spine.server.bus.given.stock.ShareAggregate;
 import io.spine.test.bus.Buy;
@@ -56,33 +55,33 @@ class DispatchingQueueSynchronisationTest {
     @DisplayName("`Bus` should not lock with its system counterpart")
     void deadlock() throws InterruptedException {
         var executor = (ThreadPoolExecutor) newFixedThreadPool(10);
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(ShareAggregate.class)
-                                     .add(new JowDonsIndex.Repository())
-        );
-        var taskCount = 10;
-        var shares =
-                Stream.generate(() -> ShareId.newBuilder()
-                        .setValue(newUuid())
-                        .build())
-                      .limit(taskCount)
-                      .collect(toImmutableList());
-        shares.forEach(share -> executor.execute(() -> {
-            var buy = Buy.newBuilder()
-                    .setShare(share)
-                    .setAmount(42)
-                    .build();
-            context.receivesCommand(buy);
-            sleepUninterruptibly(Duration.ofSeconds(1));
-            var sell = Sell.newBuilder()
-                    .setShare(share)
-                    .setAmount(12)
-                    .build();
-            context.receivesCommand(sell);
-        }));
-        executor.awaitTermination(5, SECONDS);
-        assertEquals(shares.size(), executor.getCompletedTaskCount(),
-                     "Not all tasks have been executed. Most likely, a dead lock is reached.");
+        try (var context = BlackBox.singleTenantWith(
+                ShareAggregate.class,
+                new JowDonsIndex.Repository())
+        ) {
+            var taskCount = 10;
+            var shares =
+                    Stream.generate(() -> ShareId.newBuilder()
+                                  .setValue(newUuid())
+                                  .build())
+                          .limit(taskCount)
+                          .collect(toImmutableList());
+            shares.forEach(share -> executor.execute(() -> {
+                var buy = Buy.newBuilder()
+                        .setShare(share)
+                        .setAmount(42)
+                        .build();
+                context.receivesCommand(buy);
+                sleepUninterruptibly(Duration.ofSeconds(1));
+                var sell = Sell.newBuilder()
+                        .setShare(share)
+                        .setAmount(12)
+                        .build();
+                context.receivesCommand(sell);
+            }));
+            executor.awaitTermination(5, SECONDS);
+            assertEquals(shares.size(), executor.getCompletedTaskCount(),
+                         "Not all tasks have been executed. Most likely, a dead lock is reached.");
+        }
     }
 }
diff --git a/server/src/test/java/io/spine/server/delivery/CatchUpTest.java b/server/src/test/java/io/spine/server/delivery/CatchUpTest.java
index e6616e4a563..21609ae652b 100644
--- a/server/src/test/java/io/spine/server/delivery/CatchUpTest.java
+++ b/server/src/test/java/io/spine/server/delivery/CatchUpTest.java
@@ -31,8 +31,6 @@
 import com.google.protobuf.Timestamp;
 import com.google.protobuf.util.Durations;
 import io.spine.base.Time;
-import io.spine.server.BoundedContextBuilder;
-import io.spine.server.DefaultRepository;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.delivery.given.ConsecutiveNumberProcess;
 import io.spine.server.delivery.given.ConsecutiveProjection;
@@ -168,16 +166,18 @@ class AllowCatchUp {
         @Test
         @DisplayName("if the event store is empty")
         void onEmptyEventStore() {
-            var counterCatchUp = catchUpForCounter();
-            counterCatchUp.catchUp(WhatToCatchUp.catchUpAll(aMinuteAgo()));
+            try (var counterCatchUp = catchUpForCounter()) {
+                counterCatchUp.catchUp(WhatToCatchUp.catchUpAll(aMinuteAgo()));
+            }
         }
 
         @Test
         @DisplayName("of the same instance, if the previous catch-up is already completed")
         void ifPreviousCatchUpCompleted() {
             CounterCatchUp.addOngoingCatchUpRecord(catchUpAll(aMinuteAgo()), COMPLETED);
-            var counterCatchUp = catchUpForCounter();
-            counterCatchUp.catchUp(WhatToCatchUp.catchUpAll(aMinuteAgo()));
+            try (var counterCatchUp = catchUpForCounter()) {
+                counterCatchUp.catchUp(WhatToCatchUp.catchUpAll(aMinuteAgo()));
+            }
         }
     }
 
@@ -191,9 +191,10 @@ class NotAllowSimultaneousCatchUp {
         @DisplayName("if catching up of all repository instances has started previously")
         void ifCatchUpAllStartedPreviously() {
             CounterCatchUp.addOngoingCatchUpRecord(catchUpAll(aMinuteAgo()));
-            var counterCatchUp = catchUpForCounter();
-            for (var target : counterCatchUp.targets()) {
-                assertCatchUpAlreadyStarted(counterCatchUp, target);
+            try (var counterCatchUp = catchUpForCounter()) {
+                for (var target : counterCatchUp.targets()) {
+                    assertCatchUpAlreadyStarted(counterCatchUp, target);
+                }
             }
         }
 
@@ -201,17 +202,16 @@ void ifCatchUpAllStartedPreviously() {
         @DisplayName("of the same repository instances")
         void ofSameInstances() {
             CounterCatchUp.addOngoingCatchUpRecord(catchUpOf(TARGET_ID, aMinuteAgo()));
-            var counterCatchUp = new CounterCatchUp(TARGET_ID);
-
-            assertCatchUpAlreadyStarted(counterCatchUp, TARGET_ID);
+            try (var counterCatchUp = new CounterCatchUp(TARGET_ID)) {
+                assertCatchUpAlreadyStarted(counterCatchUp, TARGET_ID);
+            }
         }
 
         @Test
         @DisplayName("of all instances if at least one catch-up of an instance is in progress")
         void ofAllIfOneAlreadyStarted() {
             CounterCatchUp.addOngoingCatchUpRecord(catchUpOf(TARGET_ID, aMinuteAgo()));
-            var counterCatchUp = new CounterCatchUp(TARGET_ID);
-            try {
+            try(var counterCatchUp = new CounterCatchUp(TARGET_ID)) {
                 counterCatchUp.catchUp(catchUpAll(aMinuteAgo()));
                 fail("It must not be possible to start catching up all the instances," +
                              " while some instance is already catching up.");
@@ -237,59 +237,60 @@ private static CounterCatchUp catchUpForCounter() {
 
     private static void testCatchUpEmpty() {
         changeShardCountTo(17);
+        try (var counterCatchUp = catchUpForCounter()) {
+            var aWhileAgo = subtract(currentTime(), Durations.fromHours(1));
+            var someTarget = "some-target";
+            counterCatchUp.catchUp(WhatToCatchUp.catchUpOf(someTarget, aWhileAgo));
 
-        var counterCatchUp = catchUpForCounter();
-        var aWhileAgo = subtract(currentTime(), Durations.fromHours(1));
-        var someTarget = "some-target";
-        counterCatchUp.catchUp(WhatToCatchUp.catchUpOf(someTarget, aWhileAgo));
-
-        var actual = counterCatchUp.find(someTarget);
-        assertThat(actual).isEmpty();
+            var actual = counterCatchUp.find(someTarget);
+            assertThat(actual).isEmpty();
+        }
     }
 
     private static void testCatchUpByIds() throws InterruptedException {
         changeShardCountTo(2);
+        try(var counterCatchUp = catchUpForCounter()) {
 
-        var counterCatchUp = catchUpForCounter();
-        var events = counterCatchUp.generateEvents(200);
+            var events = counterCatchUp.generateEvents(200);
 
-        var aWhileAgo = subtract(currentTime(), Durations.fromHours(1));
-        counterCatchUp.addHistory(aWhileAgo, events);
+            var aWhileAgo = subtract(currentTime(), Durations.fromHours(1));
+            counterCatchUp.addHistory(aWhileAgo, events);
 
-        // Round 1. Fight!
+            // Round 1. Fight!
 
-        var initialWeight = 1;
-        CounterView.changeWeightTo(initialWeight);
+            var initialWeight = 1;
+            CounterView.changeWeightTo(initialWeight);
 
-        counterCatchUp.dispatch(events, 20);
+            counterCatchUp.dispatch(events, 20);
 
-        var targets = counterCatchUp.targets();
-        var totalTargets = targets.length;
-        var initialTotals = counterCatchUp.counterValues();
-        var sumInRound = events.size() / totalTargets * initialWeight;
-        var sums = IntStream.iterate(sumInRound, i -> i)
-                            .limit(totalTargets);
-        assertThat(initialTotals).isEqualTo(sums.boxed()
-                                                .collect(toList()));
+            var targets = counterCatchUp.targets();
+            var totalTargets = targets.length;
+            var initialTotals = counterCatchUp.counterValues();
+            var sumInRound = events.size() / totalTargets * initialWeight;
+            var sums = IntStream.iterate(sumInRound, i -> i)
+                                .limit(totalTargets);
+            assertThat(initialTotals).isEqualTo(sums.boxed()
+                                                    .collect(toList()));
 
-        // Round 2. Catch up the first and the second and fight!
+            // Round 2. Catch up the first and the second and fight!
 
-        var newWeight = 100;
-        CounterView.changeWeightTo(newWeight);
-        counterCatchUp
-                .dispatchWithCatchUp(events, 20,
-                                     catchUpOf(targets[0], aWhileAgo),
-                                     catchUpOf(targets[1], aMinuteAgo()));
+            var newWeight = 100;
+            CounterView.changeWeightTo(newWeight);
+            counterCatchUp
+                    .dispatchWithCatchUp(events, 20,
+                                         catchUpOf(targets[0], aWhileAgo),
+                                         catchUpOf(targets[1], aMinuteAgo()));
 
-        var totalsAfterCatchUp = counterCatchUp.counterValues();
+            var totalsAfterCatchUp = counterCatchUp.counterValues();
 
-        var firstSumExpected = sumInRound * newWeight / initialWeight * 3;
-        var secondSumExpected = sumInRound * newWeight / initialWeight * 2;
-        var untouchedSum = sumInRound + sumInRound * newWeight / initialWeight;
-        List<Integer> expectedTotals =
-                ImmutableList.of(firstSumExpected, secondSumExpected, untouchedSum, untouchedSum);
+            var firstSumExpected = sumInRound * newWeight / initialWeight * 3;
+            var secondSumExpected = sumInRound * newWeight / initialWeight * 2;
+            var untouchedSum = sumInRound + sumInRound * newWeight / initialWeight;
+            List<Integer> expectedTotals =
+                    ImmutableList.of(firstSumExpected, secondSumExpected, untouchedSum, untouchedSum);
 
-        assertThat(totalsAfterCatchUp).isEqualTo(expectedTotals);
+            assertThat(totalsAfterCatchUp).isEqualTo(expectedTotals);
+        }
     }
 
     private static void testCatchUpAll() throws InterruptedException {
@@ -301,12 +302,9 @@ private static void testCatchUpAll() throws InterruptedException {
 
         changeShardCountTo(3);
         var projectionRepo = new ConsecutiveProjection.Repo();
-        var pmRepo =
-                DefaultRepository.of(ConsecutiveNumberProcess.class);
-        var ctx = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(projectionRepo)
-                                     .add(pmRepo)
+        var ctx = BlackBox.singleTenantWith(
+                projectionRepo,
+                ConsecutiveNumberProcess.class
         );
         var jobs = asPostCommandJobs(ctx, commands);
         post(jobs, 1);
@@ -347,6 +345,7 @@ private static void testCatchUpAll() throws InterruptedException {
                                   .state();
             assertThat(state.getLastValue()).isEqualTo(negativeExpected);
         }
+        ctx.close();
     }
 
     private static Timestamp aMinuteAgo() {
diff --git a/server/src/test/java/io/spine/server/delivery/DeliveryTest.java b/server/src/test/java/io/spine/server/delivery/DeliveryTest.java
index f8472f50955..5f0f62c4996 100644
--- a/server/src/test/java/io/spine/server/delivery/DeliveryTest.java
+++ b/server/src/test/java/io/spine/server/delivery/DeliveryTest.java
@@ -31,7 +31,6 @@
 import io.spine.base.Identifier;
 import io.spine.environment.Tests;
 import io.spine.protobuf.Messages;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.delivery.given.DeliveryTestEnv.RawMessageMemoizer;
 import io.spine.server.delivery.given.DeliveryTestEnv.ShardIndexMemoizer;
@@ -347,11 +346,10 @@ public void deliverMessagesInOrderOfEmission() throws InterruptedException {
         changeShardCountTo(20);
         TaskView.enableStrictMode();
 
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(TaskAggregate.class)
-                                     .add(new TaskAssignment.Repository())
-                                     .add(new TaskView.Repository())
+        var context = BlackBox.singleTenantWith(
+                TaskAggregate.class,
+                new TaskAssignment.Repository(),
+                new TaskView.Repository()
         );
         var commands = generateCommands(200);
         var service = newFixedThreadPool(20);
@@ -386,26 +384,25 @@ public void directDelivery() {
         var directDelivery = Delivery.direct();
         ServerEnvironment.when(Tests.class)
                          .use(directDelivery);
-
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(TaskAggregate.class)
-                                     .add(new TaskAssignment.Repository())
-                                     .add(new TaskView.Repository())
-        );
-        var commands = generateCommands(200);
-        for (var command : commands) {
-            context.receivesCommand(command);
-            var taskId = command.getId();
-            var subject = context.assertEntity(taskId, TaskView.class);
-            subject.exists();
-
-            var actualView = (TaskView) subject.actual();
-            var state = actualView.state();
-            var actualAssignee = state.getAssignee();
-
-            assertThat(state.getId()).isEqualTo(taskId);
-            assertThat(Messages.isDefault(actualAssignee)).isFalse();
+        try (var context = BlackBox.singleTenantWith(
+                TaskAggregate.class,
+                new TaskAssignment.Repository(),
+                new TaskView.Repository())
+        ) {
+            var commands = generateCommands(200);
+            for (var command : commands) {
+                context.receivesCommand(command);
+                var taskId = command.getId();
+                var subject = context.assertEntity(taskId, TaskView.class);
+                subject.exists();
+
+                var actualView = (TaskView) subject.actual();
+                var state = actualView.state();
+                var actualAssignee = state.getAssignee();
+
+                assertThat(state.getId()).isEqualTo(taskId);
+                assertThat(Messages.isDefault(actualAssignee)).isFalse();
+            }
         }
     }
 
diff --git a/server/src/test/java/io/spine/server/delivery/NastyClient.java b/server/src/test/java/io/spine/server/delivery/NastyClient.java
index bc3070b4c8e..2591103e63e 100644
--- a/server/src/test/java/io/spine/server/delivery/NastyClient.java
+++ b/server/src/test/java/io/spine/server/delivery/NastyClient.java
@@ -29,7 +29,6 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterators;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.delivery.given.CalcAggregate;
 import io.spine.server.delivery.given.CalculatorSignal;
@@ -102,46 +101,44 @@ class NastyClient {
      *         the identifiers of target entities
      */
     void runWith(Set<String> targets) {
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(repository)
-        );
-        var memoizer = subscribeToDelivered();
+        try (var context = BlackBox.singleTenantWith(repository)) {
+            var memoizer = subscribeToDelivered();
 
-        var streamSize = targets.size() * 30;
+            var streamSize = targets.size() * 30;
 
-        var targetsIterator = Iterators.cycle(targets);
-        var commands = commands(streamSize, targetsIterator);
-        var importEvents = eventsToImport(streamSize, targetsIterator);
-        var reactEvents = eventsToReact(streamSize, targetsIterator);
+            var targetsIterator = Iterators.cycle(targets);
+            var commands = commands(streamSize, targetsIterator);
+            var importEvents = eventsToImport(streamSize, targetsIterator);
+            var reactEvents = eventsToReact(streamSize, targetsIterator);
 
-        postAsync(context, commands, importEvents, reactEvents);
+            postAsync(context, commands, importEvents, reactEvents);
 
-        Stream<CalculatorSignal> signals =
-                concat(commands.stream(), importEvents.stream(), reactEvents.stream());
+            Stream<CalculatorSignal> signals =
+                    concat(commands.stream(), importEvents.stream(), reactEvents.stream());
 
-        signalsPerTarget = signals.collect(groupingBy(CalculatorSignal::getCalculatorId));
+            signalsPerTarget = signals.collect(groupingBy(CalculatorSignal::getCalculatorId));
 
-        for (var calcId : signalsPerTarget.keySet()) {
+            for (var calcId : signalsPerTarget.keySet()) {
 
-            var receivedMessages = memoizer.messagesBy(calcId);
-            Set<CalculatorSignal> targetSignals =
-                    ImmutableSet.copyOf(signalsPerTarget.get(calcId));
-            assertEquals(targetSignals, receivedMessages);
+                var receivedMessages = memoizer.messagesBy(calcId);
+                Set<CalculatorSignal> targetSignals =
+                        ImmutableSet.copyOf(signalsPerTarget.get(calcId));
+                assertEquals(targetSignals, receivedMessages);
 
-            var sumForTarget =
-                    targetSignals.stream()
-                                 .map(CalculatorSignal::getValue)
-                                 .reduce(0, Integer::sum);
-            var expectedState = Calc.newBuilder()
-                    .setId(calcId)
-                    .setSum(sumForTarget)
-                    .build();
-            context.assertState(calcId, Calc.class)
-                   .isEqualTo(expectedState);
+                var sumForTarget =
+                        targetSignals.stream()
+                                .map(CalculatorSignal::getValue)
+                                .reduce(0, Integer::sum);
+                var expectedState = Calc.newBuilder()
+                        .setId(calcId)
+                        .setSum(sumForTarget)
+                        .build();
+                context.assertState(calcId, Calc.class)
+                       .isEqualTo(expectedState);
 
+            }
+            ensureInboxesEmpty();
         }
-        ensureInboxesEmpty();
     }
 
     /**
diff --git a/server/src/test/java/io/spine/server/delivery/given/CounterCatchUp.java b/server/src/test/java/io/spine/server/delivery/given/CounterCatchUp.java
index 3349de9a177..7e2ed2c1831 100644
--- a/server/src/test/java/io/spine/server/delivery/given/CounterCatchUp.java
+++ b/server/src/test/java/io/spine/server/delivery/given/CounterCatchUp.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -31,7 +31,7 @@
 import com.google.common.collect.Iterators;
 import com.google.protobuf.Timestamp;
 import io.spine.environment.Tests;
-import io.spine.server.BoundedContextBuilder;
+import io.spine.server.Closeable;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.delivery.CatchUpStatus;
 import io.spine.server.delivery.CatchUpStorage;
@@ -58,7 +58,7 @@
  * A convenience wrapper over the {@link CounterView} repository and the {@link BlackBox}
  * Bounded Context to be used in the catch-up tests.
  */
-public class CounterCatchUp {
+public class CounterCatchUp implements Closeable {
 
     private final CounterView.Repository repo;
     private final BlackBox ctx;
@@ -67,10 +67,7 @@ public class CounterCatchUp {
     public CounterCatchUp(String... ids) {
         this.ids = ids.clone();
         this.repo = new CounterView.Repository();
-        this.ctx = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(repo)
-        );
+        this.ctx = BlackBox.singleTenantWith(repo);
     }
 
     public void addHistory(Timestamp when, List<NumberAdded> events) {
@@ -179,4 +176,14 @@ var record = TestCatchUpJobs.catchUpJob(
         ServerEnvironment.when(Tests.class)
                          .use(delivery);
     }
+
+    @Override
+    public void close() {
+        ctx.close();
+    }
+
+    @Override
+    public boolean isOpen() {
+        return ctx.isOpen();
+    }
 }
diff --git a/server/src/test/java/io/spine/server/delivery/given/ReceptionFailureTestEnv.java b/server/src/test/java/io/spine/server/delivery/given/ReceptionFailureTestEnv.java
index 6bfc643a6ee..a80923e80fe 100644
--- a/server/src/test/java/io/spine/server/delivery/given/ReceptionFailureTestEnv.java
+++ b/server/src/test/java/io/spine/server/delivery/given/ReceptionFailureTestEnv.java
@@ -28,7 +28,6 @@
 
 import com.google.common.collect.ImmutableList;
 import io.spine.environment.Tests;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.DefaultRepository;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.delivery.Delivery;
@@ -60,10 +59,7 @@ private ReceptionFailureTestEnv() {
 
     public static BlackBox blackBox() {
         var repository = DefaultRepository.of(ReceptionistAggregate.class);
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(repository)
-        );
+        var context = BlackBox.singleTenantWith(repository);
         return context;
     }
 
diff --git a/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java b/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
index ab61b9a6182..aaedc006721 100644
--- a/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
+++ b/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
@@ -108,10 +108,7 @@ void withCause() {
     }
 
     private static BlackBox context() {
-        return BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(CardAggregate.class)
-        );
+        return BlackBox.singleTenantWith(CardAggregate.class);
     }
 
     private static BorrowBooks borrowBooks(UserId reader) {
diff --git a/server/src/test/java/io/spine/server/migration/mirror/given/MirrorMigrationTestEnv.java b/server/src/test/java/io/spine/server/migration/mirror/given/MirrorMigrationTestEnv.java
index 20c526ff6a3..7ddb1e740cc 100644
--- a/server/src/test/java/io/spine/server/migration/mirror/given/MirrorMigrationTestEnv.java
+++ b/server/src/test/java/io/spine/server/migration/mirror/given/MirrorMigrationTestEnv.java
@@ -27,7 +27,6 @@
 package io.spine.server.migration.mirror.given;
 
 import io.spine.environment.Tests;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.entity.storage.EntityRecordStorage;
 import io.spine.server.migration.mirror.MirrorStorage;
@@ -54,10 +53,7 @@ public static void assertWithinBc(EntityRecordStorage<ParcelId, Parcel> entityRe
         ServerEnvironment.when(Tests.class)
                          .use(PreparedStorageFactory.with(entityRecordStorage));
 
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(ParcelAgg.class)
-        );
+        var context = BlackBox.singleTenantWith(ParcelAgg.class);
         var client = context.clients()
                             .withMatchingTenant()
                             .asGuest();
diff --git a/server/src/test/java/io/spine/server/model/handler/MessageInterfaceResultTest.java b/server/src/test/java/io/spine/server/model/handler/MessageInterfaceResultTest.java
index db96e862c96..e14016a2af2 100644
--- a/server/src/test/java/io/spine/server/model/handler/MessageInterfaceResultTest.java
+++ b/server/src/test/java/io/spine/server/model/handler/MessageInterfaceResultTest.java
@@ -26,7 +26,6 @@
 
 package io.spine.server.model.handler;
 
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.aggregate.model.AggregateClass;
 import io.spine.server.model.handler.given.RoverBot;
 import io.spine.server.model.handler.given.command.Start;
@@ -52,10 +51,7 @@ class MessageInterfaceResultTest {
 
     @BeforeEach
     void createContext() {
-        context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(RoverBot.class)
-        );
+        context = BlackBox.singleTenantWith(RoverBot.class);
     }
 
     @AfterEach
diff --git a/server/src/test/java/io/spine/server/procman/ProcessManagerRepositoryTest.java b/server/src/test/java/io/spine/server/procman/ProcessManagerRepositoryTest.java
index 9d3bd806d40..9983c3497f9 100644
--- a/server/src/test/java/io/spine/server/procman/ProcessManagerRepositoryTest.java
+++ b/server/src/test/java/io/spine/server/procman/ProcessManagerRepositoryTest.java
@@ -596,10 +596,7 @@ void postEventsThroughFilter() {
                 .newBuilder()
                 .setProjectId(projectId)
                 .build();
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(new EventDiscardingProcManRepository())
-        );
+        var context = BlackBox.singleTenantWith(new EventDiscardingProcManRepository());
 
         context.receivesCommand(command)
                .assertEvents()
diff --git a/server/src/test/java/io/spine/server/projection/StateRoutingTest.java b/server/src/test/java/io/spine/server/projection/StateRoutingTest.java
index 7f0f40e9ce7..267150abf3f 100644
--- a/server/src/test/java/io/spine/server/projection/StateRoutingTest.java
+++ b/server/src/test/java/io/spine/server/projection/StateRoutingTest.java
@@ -29,7 +29,6 @@
 import com.google.protobuf.StringValue;
 import io.spine.base.Identifier;
 import io.spine.protobuf.AnyPacker;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.route.given.sur.ArtistMood;
 import io.spine.server.route.given.sur.ArtistMoodRepo;
 import io.spine.server.route.given.sur.Gallery;
@@ -55,13 +54,11 @@ class StateRoutingTest {
 
     @BeforeEach
     void setupContext() {
-        context = BlackBox.from(
-                BoundedContextBuilder
-                        .assumingTests()
-                        .add(MagazineAggregate.class)
-                        .add(new ArtistMoodRepo())
-                        .add(new Gallery())
-                        .add(WorksProjection.class)
+        context = BlackBox.singleTenantWith(
+                MagazineAggregate.class,
+                new ArtistMoodRepo(),
+                new Gallery(),
+                WorksProjection.class
         );
     }
 
diff --git a/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java b/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
index d019c75f037..9a473f50db8 100644
--- a/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
+++ b/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,6 @@
 import io.spine.core.MessageId;
 import io.spine.core.UserId;
 import io.spine.protobuf.TypeConverter;
-import io.spine.server.BoundedContext;
 import io.spine.server.BoundedContextBuilder;
 import io.spine.server.ServerEnvironment;
 import io.spine.server.given.groups.GroupId;
@@ -82,26 +81,26 @@ void receiveUpdates() {
         var firstTaskAdded = GivenEventMessage.taskAdded();
         var secondTaskAdded = GivenEventMessage.taskAdded();
         var producerId = created.getProjectId();
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                                     .add(new EntitySubscriberProjection.Repository())
-                                     .add(new TestProjection.Repository())
-        );
-
-        context.receivesEventsProducedBy(producerId,
-                                         created,
-                                         firstTaskAdded,
-                                         secondTaskAdded);
-
-        context.assertState(
-                producerId,
-                ProjectTaskNames.newBuilder()
-                        .setProjectId(producerId)
-                        .setProjectName(created.getName())
-                        .addTaskName(firstTaskAdded.getTask().getTitle())
-                        .addTaskName(secondTaskAdded.getTask().getTitle())
-                        .build()
-        );
+        try (var context = BlackBox.singleTenantWith(
+                new EntitySubscriberProjection.Repository(),
+                new TestProjection.Repository())
+        ) {
+            context.receivesEventsProducedBy(producerId,
+                                             created,
+                                             firstTaskAdded,
+                                             secondTaskAdded);
+            context.assertState(
+                    producerId,
+                    ProjectTaskNames.newBuilder()
+                            .setProjectId(producerId)
+                            .setProjectName(created.getName())
+                            .addTaskName(firstTaskAdded.getTask()
+                                                       .getTitle())
+                            .addTaskName(secondTaskAdded.getTask()
+                                                        .getTitle())
+                            .build()
+            );
+        }
     }
 
     @Test
@@ -109,14 +108,8 @@ void receiveUpdates() {
     void receiveExternal() {
         var established = GivenEventMessage.organizationEstablished();
 
-        var sender = BlackBox.from(
-                BoundedContext.singleTenant("Organizations")
-                              .add(new OrganizationProjection.Repository())
-        );
-        var receiver = BlackBox.from(
-                BoundedContext.singleTenant("Groups")
-                .add(new GroupNameProjection.Repository())
-        );
+        var sender = BlackBox.singleTenant("Organizations", new OrganizationProjection.Repository());
+        var receiver = BlackBox.singleTenant("Groups", new GroupNameProjection.Repository());
 
         var producerId = established.getId();
         sender.receivesEventsProducedBy(producerId, established);
diff --git a/server/src/test/java/io/spine/server/stand/EntityQueryProcessorTest.java b/server/src/test/java/io/spine/server/stand/EntityQueryProcessorTest.java
index 1c060c482ec..409ece8357e 100644
--- a/server/src/test/java/io/spine/server/stand/EntityQueryProcessorTest.java
+++ b/server/src/test/java/io/spine/server/stand/EntityQueryProcessorTest.java
@@ -33,7 +33,6 @@
 import io.spine.client.QueryFactory;
 import io.spine.client.QueryId;
 import io.spine.client.Target;
-import io.spine.server.BoundedContext;
 import io.spine.server.projection.ProjectionRepository;
 import io.spine.server.stand.given.MenuRepository;
 import io.spine.system.server.Mirror;
@@ -73,9 +72,7 @@ class EntityQueryProcessorTest {
     @BeforeEach
     void setUp() {
         ProjectionRepository<?, ?, ?> repository = new MenuRepository();
-        context = BlackBox.from(
-                BoundedContext.singleTenant("Cafeteria")
-                              .add(repository));
+        context = BlackBox.singleTenant("Cafeteria", repository);
         processor = new EntityQueryProcessor(repository);
         fill();
     }
diff --git a/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java b/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
index 6e2fababf7b..765ecf77816 100644
--- a/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
+++ b/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
@@ -43,6 +43,7 @@
 
 import static io.spine.base.Identifier.newUuid;
 import static io.spine.system.server.given.diagnostics.ViolationsWatch.DEFAULT;
+import static io.spine.testing.server.blackbox.BlackBox.singleTenantWith;
 
 @DisplayName("`ConstraintViolated` should be emitted when")
 class ConstraintViolatedTest {
@@ -51,50 +52,48 @@ class ConstraintViolatedTest {
     @MuteLogging
     @DisplayName("an entity state is set to an invalid value as a result of an event")
     void afterEvent() {
-        var invalidText = "123-non numerical";
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                    .add(ValidatedAggregate.class)
-                    .add(new ViolationsWatch.Repository())
-        ).tolerateFailures();
-        context.receivesCommand(
-                ValidateAndSet.newBuilder()
-                              .setId(ValidatedId.generate())
-                              .setTextToValidate(invalidText)
-                              .build()
-        );
-        context.assertEntity(DEFAULT, ViolationsWatch.class)
-               .hasStateThat()
-               .isEqualTo(InvalidText.newBuilder()
-                                     .setId(DEFAULT)
-                                     .setInvalidText(invalidText)
-                                     .buildPartial()
-               );
+        try (var context = singleTenantWith(
+                     ValidatedAggregate.class,
+                     new ViolationsWatch.Repository()
+             ).tolerateFailures()
+        ) {
+            var invalidText = "123-non numerical";
+            context.receivesCommand(
+                    ValidateAndSet.newBuilder()
+                            .setId(ValidatedId.generate())
+                            .setTextToValidate(invalidText)
+                            .build()
+            );
+            context.assertEntity(DEFAULT, ViolationsWatch.class)
+                   .hasStateThat()
+                   .isEqualTo(InvalidText.newBuilder()
+                                      .setId(DEFAULT)
+                                      .setInvalidText(invalidText)
+                                      .buildPartial()
+                   );
+        }
     }
 
     @Test
     @MuteLogging
     @DisplayName("an entity state is set to an invalid value as a result of a command")
     void afterCommand() {
-        var context = BlackBox.from(
-                BoundedContextBuilder.assumingTests()
-                .add(VerificationProcman.class)
-                .add(new ViolationsWatch.Repository())
-        ).tolerateFailures();
-        context.receivesCommand(
-                StartVerification
-                        .newBuilder()
-                        .setUserId(UserId.newBuilder()
-                                         .setValue(newUuid()))
-                        .setAddress(EmailAddress.newBuilder()
-                                                .setValue("a@b.c"))
-                        .build()
-        );
-        context.assertEntity(DEFAULT, ViolationsWatch.class)
-               .hasStateThat()
-               .isEqualTo(InvalidText.newBuilder()
-                                     .setId(DEFAULT)
-                                     .setErrorMessage("A value must be set.")
-                                     .buildPartial());
+        try (var context = singleTenantWith(VerificationProcman.class,
+                                            new ViolationsWatch.Repository())
+                .tolerateFailures()
+        ) {
+            context.receivesCommand(
+                    StartVerification.newBuilder()
+                            .setUserId(UserId.newBuilder().setValue(newUuid()))
+                            .setAddress(EmailAddress.newBuilder().setValue("a@b.c"))
+                            .build()
+            );
+            context.assertEntity(DEFAULT, ViolationsWatch.class)
+                   .hasStateThat()
+                   .isEqualTo(InvalidText.newBuilder()
+                                      .setId(DEFAULT)
+                                      .setErrorMessage("A value must be set.")
+                                      .buildPartial());
+        }
     }
 }
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index 88813aa3487..edc40fa1c51 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -61,6 +61,7 @@
 import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Collection;
@@ -76,6 +77,7 @@
 import static io.spine.grpc.StreamObservers.memoizingObserver;
 import static io.spine.server.entity.model.EntityClass.stateClassOf;
 import static io.spine.testing.server.blackbox.Actor.defaultActor;
+import static io.spine.util.Exceptions.newIllegalArgumentException;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.synchronizedSet;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -127,16 +129,105 @@ public abstract class BlackBox implements WithLogging, Closeable {
     private final Set<Event> postedEvents;
 
     /**
-     * Creates new instance obtaining configuration parameters from the passed builder.
+     * Creates new instance obtaining configuration parameters from the given context instance.
      */
-    public static BlackBox from(BoundedContextBuilder builder) {
-        var context = builder.build();
-        var box = builder.isMultitenant()
+    public static BlackBox from(BoundedContext context) {
+        var box = context.isMultitenant()
                   ? new MtBlackBox(context)
                   : new StBlackBox(context);
         return box;
     }
 
+    /**
+     * Creates new instance obtaining configuration parameters from the passed builder.
+     */
+    public static BlackBox from(BoundedContextBuilder builder) {
+        var context = builder.build();
+        return from(context);
+    }
+
+    /**
+     * Creates a {@code BlackBox} over a single-tenant context with the given components.
+     *
+     * @see #with(boolean, Object...)
+     */
+    public static BlackBox singleTenantWith(Object... components) {
+        return with(false, components);
+    }
+
+    /**
+     * Creates a {@code BlackBox} over a single-tenant context with the given name and components.
+     *
+     * @see #with(boolean, Object...)
+     */
+    public static BlackBox singleTenant(String name, Object... components) {
+        return with(BoundedContext.singleTenant(name), components);
+    }
+
+    /**
+     * Creates a {@code BlackBox} over a multi-tenant context with the given components.
+     *
+     * @see #with(boolean, Object...)
+     */
+    public static BlackBox multiTenantWith(Object... components) {
+        return with(false, components);
+    }
+
+    /**
+     * Creates a {@code BlackBox} over a context with the given components.
+     *
+     * <p>The components can be either {@link Repository} or {@link Entity} classes.
+     *
+     * <p>For creating a test environment with other components, please use
+     * {@link BoundedContextBuilder} and then {@link #from(BoundedContext)}.
+     *
+     * @param multitenant
+     *         whether the context under the test is multitenant
+     * @param components
+     *         repositories or entity classes to be added to the context under the test
+     */
+    public static BlackBox with(boolean multitenant, Object... components) {
+        var builder = BoundedContextBuilder.assumingTests(multitenant);
+        return with(builder, components);
+    }
+
+    /**
+     * Creates a {@code BlackBox} over a context with the given components.
+     *
+     * <p>The components can be either {@link Repository} or {@link Entity} classes.
+     *
+     * <p>For creating a test environment with other components, please use
+     * {@link BoundedContextBuilder} and then {@link #from(BoundedContext)}.
+     *
+     * @param builder
+     *         the context builder to use for creating the context under the test
+     * @param components
+     *         repositories or entity classes to be added to the context under the test
+     */
+    public static BlackBox with(BoundedContextBuilder builder, Object... components) {
+        for (var c : components) {
+            if (c instanceof Repository) {
+                builder.add((Repository<?, ?>) c);
+            } else if (c instanceof Class<?>) {
+                if (Entity.class.isAssignableFrom((Class<?>) c)) {
+                    var entityClass = cast((Class<?>)c);
+                    builder.add(entityClass);
+                }
+            } else {
+                throw newIllegalArgumentException(
+                        "Unsupported component type: `%s`.", c.getClass().getName()
+                );
+            }
+        }
+        return from(builder);
+    }
+
+    private static <I, E extends Entity<I, ?>> Class<? extends E> cast(Class<?> cls) {
+        @SuppressWarnings("unchecked") // Safe due to the `isAssignableFrom` check.
+        var result = (Class<? extends E>) cls;
+        return result;
+    }
+
     BlackBox(BoundedContext context) {
         super();
         this.context = context;
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/ClientFactory.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/ClientFactory.java
index 02394440679..8c4286bbdcc 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/ClientFactory.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/ClientFactory.java
@@ -156,7 +156,7 @@ private void initServer() {
      */
     @Override
     @SuppressWarnings("TestOnlyProblems" /* Calling the production-level method. */)
-    public void close() throws Exception {
+    public void close() {
         if (!isOpen() || isNull(grpcContainer)) {
             return;
         }

From 514c4ed14bd2ebf08d420eddbb4fec3f0365549d Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 01:23:28 +0000
Subject: [PATCH 18/32] Bump version -> `2.0.0-SNAPSHOT.170`

---
 pom.xml            | 2 +-
 version.gradle.kts | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/pom.xml b/pom.xml
index c044183239c..6b4a78f8508 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,7 +10,7 @@ all modules and does not describe the project structure per-subproject.
  -->
 <groupId>io.spine</groupId>
 <artifactId>spine-core-java</artifactId>
-<version>2.0.0-SNAPSHOT.161</version>
+<version>2.0.0-SNAPSHOT.170</version>
 
 <inceptionYear>2015</inceptionYear>
 
diff --git a/version.gradle.kts b/version.gradle.kts
index 6549ecbd082..3d1fb0002eb 100644
--- a/version.gradle.kts
+++ b/version.gradle.kts
@@ -29,4 +29,4 @@
  *
  * For versions of Spine-based dependencies, please see [io.spine.internal.dependency.Spine].
  */
-val versionToPublish: String by extra("2.0.0-SNAPSHOT.161")
+val versionToPublish: String by extra("2.0.0-SNAPSHOT.170")

From 78c5073c01b2f5d4f0680fff48b4e74a8787efd8 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 01:32:41 +0000
Subject: [PATCH 19/32] Do not catch exception not thrown

---
 server/src/main/java/io/spine/server/Closeable.java | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/server/src/main/java/io/spine/server/Closeable.java b/server/src/main/java/io/spine/server/Closeable.java
index 0dfb73f1017..091743bad64 100644
--- a/server/src/main/java/io/spine/server/Closeable.java
+++ b/server/src/main/java/io/spine/server/Closeable.java
@@ -75,11 +75,7 @@ default void checkOpen() throws IllegalStateException {
      */
     default void closeIfOpen() {
         if (isOpen()) {
-            try {
-                close();
-            } catch (Exception e) {
-                throw illegalStateWithCauseOf(e);
-            }
+            close();
         }
     }
 }

From 6035903d5244f7ec58d0f51d98ecd40a6698a354 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 01:35:55 +0000
Subject: [PATCH 20/32] Document the interface

---
 .../main/java/io/spine/server/bus/DelegatingDispatcher.java | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
index ed21cdd714b..0f896e91d06 100644
--- a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
+++ b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
@@ -30,6 +30,12 @@
 import io.spine.server.type.MessageEnvelope;
 import io.spine.type.MessageClass;
 
+/**
+ * A dispatcher which delegates the responsibilities to an aggregated {@link DispatcherDelegate}.
+ *
+ * @param <C> the type of the message class
+ * @param <E> the type of the message envelope
+ */
 @Internal
 public interface DelegatingDispatcher<C extends MessageClass<?>,
                                       E extends MessageEnvelope<?, ?, ?>>

From 369b3a689210702c5d4e635343208924f3a6c7e0 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 02:17:41 +0000
Subject: [PATCH 21/32] Do not require wrapping exceptions on `close()`

---
 .../testing/server/blackbox/BlackBox.java     |  8 ++---
 .../testing/server/blackbox/BlackBoxTest.java | 31 ++++++++++++-------
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index edc40fa1c51..f7730b5b3aa 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -61,7 +61,6 @@
 import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
-import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Collection;
@@ -170,7 +169,7 @@ public static BlackBox singleTenant(String name, Object... components) {
      * @see #with(boolean, Object...)
      */
     public static BlackBox multiTenantWith(Object... components) {
-        return with(false, components);
+        return with(true, components);
     }
 
     /**
@@ -204,6 +203,7 @@ public static BlackBox with(boolean multitenant, Object... components) {
      * @param components
      *         repositories or entity classes to be added to the context under the test
      */
+    @SuppressWarnings("ChainOfInstanceofChecks") // We allow passing `Object`s to simplify setup.
     public static BlackBox with(BoundedContextBuilder builder, Object... components) {
         for (var c : components) {
             if (c instanceof Repository) {
@@ -583,8 +583,8 @@ private ImmutableList<Command> commands() {
     abstract ImmutableList<Command> select(CommandCollector collector);
 
     /**
-     * Obtains immutable list of events generated in this Bounded Context in response to posted
-     * messages.
+     * Obtains an immutable list of events generated in this Bounded Context in response
+     * to posted messages.
      *
      * <p>The returned list does <em>NOT</em> contain events posted to this Bounded Context
      * during test setup.
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
index 0fba5f4e419..4c0ef026b1d 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
@@ -450,7 +450,7 @@ void multiple() {
     }
 
     @Test
-    @DisplayName("throw `IllegalStateException` on Bounded Context close error")
+    @DisplayName("pass exception thrown when 'Bounded Context' is closed")
     void throwIllegalStateExceptionOnClose() {
         var throwingRepo = new RepositoryThrowingExceptionOnClose() {
             @Override
@@ -459,11 +459,9 @@ protected void throwException() {
             }
         };
 
-        var ctx = BlackBox.from(
-                newBuilder().add(throwingRepo)
-        );
-
-        assertThrows(IllegalStateException.class, ctx::close);
+        try (var ctx = BlackBox.singleTenantWith(throwingRepo)) {
+            assertThrows(RuntimeException.class, ctx::close);
+        }
     }
 
     @Nested
@@ -496,16 +494,14 @@ void setUp() {
 
         @Test
         void singleTenant() {
-            var builder = BoundedContextBuilder
-                    .assumingTests(false)
+            var builder = BoundedContextBuilder.assumingTests(false)
                     .enrichEventsUsing(enricher);
             assertBlackBox(builder, StBlackBox.class);
         }
 
         @Test
         void multiTenant() {
-            var builder = BoundedContextBuilder
-                    .assumingTests(true)
+            var builder = BoundedContextBuilder.assumingTests(true)
                     .setTenantIndex(tenantIndex)
                     .enrichEventsUsing(enricher);
             assertBlackBox(builder, MtBlackBox.class);
@@ -580,7 +576,7 @@ private void assertEnricher() {
         }
 
         private void assertTenantIndex() {
-            if(context().isMultitenant()) {
+            if (context().isMultitenant()) {
                 assertThat(tenantIndex())
                         .isSameInstanceAs(tenantIndex);
             }
@@ -609,6 +605,19 @@ private Set<TypeName> toTypes(Iterable<Repository<?, ?>> repos) {
         }
     }
 
+    @Nested
+    @DisplayName("clreate an instance using passed components")
+    class CreateWith {
+
+        @Test
+        @DisplayName("multitenant")
+        void multitenant() {
+            try(var ctx = BlackBox.multiTenantWith(new BbProjectRepository())) {
+                assertThat(ctx.context().isMultitenant()).isTrue();
+            }
+        }
+    }
+
     @Nested
     @DisplayName("obtain `EntitySubject`")
     class ObtainEntitySubject {

From 6576993d7dab402472408d5c542e2ec364e5489b Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 02:28:43 +0000
Subject: [PATCH 22/32] Improve documentation

---
 server/src/main/java/io/spine/server/bus/Bus.java      |  2 +-
 .../java/io/spine/server/bus/DispatcherDelegate.java   | 10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 389d56437ae..344f65de062 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, TeamDev. All rights reserved.
+ * Copyright 2023, TeamDev. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
index 17fd40fe0f2..1fc322ab1ce 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
@@ -29,7 +29,11 @@
 import io.spine.server.type.MessageEnvelope;
 import io.spine.type.MessageClass;
 
-public interface DispatcherDelegate<C extends MessageClass<?>,
-                                    E extends MessageEnvelope<?, ?, ?>> {
-
+/**
+ * A delegate of a {@link DelegatingDispatcher}.
+ *
+ * @param <C> the type of the dispatched message class
+ * @param <E> the type of the message envelope
+ */
+public interface DispatcherDelegate<C extends MessageClass<?>, E extends MessageEnvelope<?, ?, ?>> {
 }

From 5fabf274919e5b163972b7fed3f602b0dce44c38 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 02:38:22 +0000
Subject: [PATCH 23/32] Optimise imports

---
 server/src/main/java/io/spine/server/Closeable.java            | 1 -
 server/src/main/java/io/spine/server/transport/ChannelHub.java | 2 +-
 .../io/spine/server/aggregate/AggregateRepositoryTest.java     | 2 +-
 .../java/io/spine/server/log/AbstractEntityLoggingTest.java    | 1 -
 .../io/spine/server/projection/e2e/ProjectionEndToEndTest.java | 3 +--
 .../java/io/spine/system/server/ConstraintViolatedTest.java    | 2 --
 .../java/io/spine/testing/server/blackbox/BlackBoxTest.java    | 1 -
 7 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/server/src/main/java/io/spine/server/Closeable.java b/server/src/main/java/io/spine/server/Closeable.java
index 091743bad64..dadb82675d9 100644
--- a/server/src/main/java/io/spine/server/Closeable.java
+++ b/server/src/main/java/io/spine/server/Closeable.java
@@ -27,7 +27,6 @@
 package io.spine.server;
 
 import static com.google.common.base.Preconditions.checkState;
-import static io.spine.util.Exceptions.illegalStateWithCauseOf;
 
 /**
  * Base interface for server-side objects that may hold resources that need to be released
diff --git a/server/src/main/java/io/spine/server/transport/ChannelHub.java b/server/src/main/java/io/spine/server/transport/ChannelHub.java
index da12b2dbace..f09c181f321 100644
--- a/server/src/main/java/io/spine/server/transport/ChannelHub.java
+++ b/server/src/main/java/io/spine/server/transport/ChannelHub.java
@@ -103,7 +103,7 @@ private Set<ChannelId> detectStale() {
             if (channel.isStale()) {
                 try {
                     channel.close();
-                } catch (Exception e) {
+                } catch (RuntimeException e) {
                     throw illegalStateWithCauseOf(e);
                 } finally {
                     toRemove.add(channelId);
diff --git a/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java b/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
index 91a821ae363..e437f248f17 100644
--- a/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
+++ b/server/src/test/java/io/spine/server/aggregate/AggregateRepositoryTest.java
@@ -114,7 +114,7 @@ void setUp() {
     }
 
     @AfterEach
-    void tearDown() throws Exception {
+    void tearDown() {
         context().close();
     }
 
diff --git a/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java b/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
index aaedc006721..f664a3fdb1b 100644
--- a/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
+++ b/server/src/test/java/io/spine/server/log/AbstractEntityLoggingTest.java
@@ -27,7 +27,6 @@
 package io.spine.server.log;
 
 import io.spine.core.UserId;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.server.log.given.Books;
 import io.spine.server.log.given.CardAggregate;
 import io.spine.testing.core.given.GivenUserId;
diff --git a/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java b/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
index 9a473f50db8..ca1224c5ebb 100644
--- a/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
+++ b/server/src/test/java/io/spine/server/projection/e2e/ProjectionEndToEndTest.java
@@ -126,8 +126,7 @@ void receiveExternal() {
 
     @Test
     @DisplayName("receive entity state updates along with system event context")
-    @SuppressWarnings("OverlyCoupledMethod")
-    void receiveEntityStateUpdatesAndEventContext() throws Exception {
+    void receiveEntityStateUpdatesAndEventContext() {
         var repository = new GroupProjection.Repository();
         var groups = BoundedContextBuilder.assumingTests().build();
         groups.internalAccess()
diff --git a/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java b/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
index 765ecf77816..df48e0ae8d9 100644
--- a/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
+++ b/server/src/test/java/io/spine/system/server/ConstraintViolatedTest.java
@@ -28,7 +28,6 @@
 
 import io.spine.core.UserId;
 import io.spine.net.EmailAddress;
-import io.spine.server.BoundedContextBuilder;
 import io.spine.system.server.given.diagnostics.ValidatedAggregate;
 import io.spine.system.server.given.diagnostics.VerificationProcman;
 import io.spine.system.server.given.diagnostics.ViolationsWatch;
@@ -37,7 +36,6 @@
 import io.spine.system.server.test.ValidateAndSet;
 import io.spine.system.server.test.ValidatedId;
 import io.spine.testing.logging.mute.MuteLogging;
-import io.spine.testing.server.blackbox.BlackBox;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
index 4c0ef026b1d..b1651a44472 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
@@ -875,7 +875,6 @@ void linkedToTheContextUnderTest() {
 
         @Test
         @DisplayName("closed as `BlackBoxContext` is closed")
-        @SuppressWarnings("ResultOfMethodCallIgnored")  /* Expecting an exception. */
         void closedAsBlackBoxContextClosed() {
             var factory = context().clients();
             var client = factory.withMatchingTenant();

From 23e745d1472582092c182fba8c9e04af02cd77c0 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 02:42:40 +0000
Subject: [PATCH 24/32] Revert formatting

---
 .../main/java/io/spine/server/stand/InMemoryTypeRegistry.java   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java b/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
index d5c78e2e74f..ee3d22492a7 100644
--- a/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
+++ b/server/src/main/java/io/spine/server/stand/InMemoryTypeRegistry.java
@@ -71,7 +71,7 @@ static TypeRegistry newInstance() {
 
         if (repository instanceof QueryableRepository) {
             @SuppressWarnings("unchecked")  /* Guaranteed by the `QueryableRepository` contract. */
-                    var recordRepo = (QueryableRepository<I, ?>) repository;
+            var recordRepo = (QueryableRepository<I, ?>) repository;
             repositories.put(entityType, recordRepo);
         }
         if (repository instanceof AggregateRepository) {

From df8a53e42b98fd871c5d994c0fd30cc420cd78d0 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 15:10:47 +0000
Subject: [PATCH 25/32] Document generic parameters

---
 .../java/io/spine/server/bus/DelegatingDispatcher.java |  6 ++++--
 .../java/io/spine/server/bus/DispatcherDelegate.java   | 10 ++++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
index 0f896e91d06..3cc997c6681 100644
--- a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
+++ b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
@@ -33,8 +33,10 @@
 /**
  * A dispatcher which delegates the responsibilities to an aggregated {@link DispatcherDelegate}.
  *
- * @param <C> the type of the message class
- * @param <E> the type of the message envelope
+ * @param <C>
+ *         the type of the message class
+ * @param <E>
+ *         the type of the message envelope
  */
 @Internal
 public interface DelegatingDispatcher<C extends MessageClass<?>,
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
index 1fc322ab1ce..4c550b4ae52 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
@@ -32,8 +32,14 @@
 /**
  * A delegate of a {@link DelegatingDispatcher}.
  *
- * @param <C> the type of the dispatched message class
- * @param <E> the type of the message envelope
+ * @param <C>
+ *         the type of the dispatched message class
+ * @param <E>
+ *         the type of the message envelope
+ * @apiNote The generic parameters are the same as the ones of the {@link DelegatingDispatcher}
+ *      to which this delegate belongs. Even though they are not used in this interface directly,
+ *      they bring semantic meaning to the interface and code clarity at the usage sites.
  */
+@SuppressWarnings("unused")
 public interface DispatcherDelegate<C extends MessageClass<?>, E extends MessageEnvelope<?, ?, ?>> {
 }

From b7d4545c55c9bee5a33ca95beb18653b377c0612 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 15:11:36 +0000
Subject: [PATCH 26/32] Bump `base` -> `2.0.0-SNAPSHOT.191`

---
 buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
index 490fbf4f66c..08a521241b2 100644
--- a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
+++ b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
@@ -45,7 +45,7 @@ object Spine {
          *
          * @see <a href="https://github.com/SpineEventEngine/base">spine-base</a>
          */
-        const val base = "2.0.0-SNAPSHOT.190"
+        const val base = "2.0.0-SNAPSHOT.191"
 
         /**
          * The version of [Spine.reflect].

From edf6a01b7579034e5a8fc2c45a92f328c24fe73c Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 15:41:51 +0000
Subject: [PATCH 27/32] Remove `Probe` to `BlackBoxProbe`

---
 .../io/spine/testing/server/blackbox/BlackBox.java    | 11 ++++++++---
 .../blackbox/probe/{Probe.java => BlackboxProbe.java} |  4 ++--
 .../spine/testing/server/blackbox/BlackBoxTest.java   |  4 ++--
 3 files changed, 12 insertions(+), 7 deletions(-)
 rename testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/{Probe.java => BlackboxProbe.java} (97%)

diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
index f7730b5b3aa..125cf54dcb6 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/BlackBox.java
@@ -57,7 +57,7 @@
 import io.spine.testing.server.EventSubject;
 import io.spine.testing.server.blackbox.probe.CommandCollector;
 import io.spine.testing.server.blackbox.probe.EventCollector;
-import io.spine.testing.server.blackbox.probe.Probe;
+import io.spine.testing.server.blackbox.probe.BlackboxProbe;
 import io.spine.testing.server.entity.EntitySubject;
 import io.spine.testing.server.query.QueryResultSubject;
 import io.spine.time.ZoneId;
@@ -70,6 +70,7 @@
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.Lists.asList;
@@ -99,7 +100,7 @@ public abstract class BlackBox implements WithLogging, Closeable {
     /**
      * The probe inserted into the context under the test.
      */
-    private final Probe probe;
+    private final BlackboxProbe probe;
 
     /**
      * A factory of {@link Client}s which send requests to this context.
@@ -169,6 +170,7 @@ public static BlackBox singleTenant(String name, Object... components) {
      * @see #with(boolean, Object...)
      */
     public static BlackBox multiTenantWith(Object... components) {
+        checkNotNull(components);
         return with(true, components);
     }
 
@@ -186,6 +188,7 @@ public static BlackBox multiTenantWith(Object... components) {
      *         repositories or entity classes to be added to the context under the test
      */
     public static BlackBox with(boolean multitenant, Object... components) {
+        checkNotNull(components);
         var builder = BoundedContextBuilder.assumingTests(multitenant);
         return with(builder, components);
     }
@@ -205,7 +208,9 @@ public static BlackBox with(boolean multitenant, Object... components) {
      */
     @SuppressWarnings("ChainOfInstanceofChecks") // We allow passing `Object`s to simplify setup.
     public static BlackBox with(BoundedContextBuilder builder, Object... components) {
+        checkNotNull(components);
         for (var c : components) {
+            checkArgument(c != null, "Null component is not allowed.");
             if (c instanceof Repository) {
                 builder.add((Repository<?, ?>) c);
             } else if (c instanceof Class<?>) {
@@ -231,7 +236,7 @@ public static BlackBox with(BoundedContextBuilder builder, Object... components)
     BlackBox(BoundedContext context) {
         super();
         this.context = context;
-        this.probe = new Probe();
+        this.probe = new BlackboxProbe();
         context.install(probe);
         this.clientFactory = new ClientFactory(context);
         this.actor = defaultActor();
diff --git a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/BlackboxProbe.java
similarity index 97%
rename from testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
rename to testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/BlackboxProbe.java
index d52d69939ff..4b67f55a1ff 100644
--- a/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/Probe.java
+++ b/testutil-server/src/main/java/io/spine/testing/server/blackbox/probe/BlackboxProbe.java
@@ -40,7 +40,7 @@
  * {@link io.spine.testing.server.blackbox.BlackBox BlackBox} to collect
  * commands and events produced by a {@link BoundedContext} being tested.
  */
-public class Probe implements BoundedContext.Probe {
+public final class BlackboxProbe implements BoundedContext.Probe {
 
     private @Nullable BoundedContext context;
 
@@ -64,7 +64,7 @@ public class Probe implements BoundedContext.Probe {
     /**
      * Creates a new instance.
      */
-    public Probe() {
+    public BlackboxProbe() {
         this.commands = new CommandCollector();
         this.events = new EventCollector();
         this.failedHandlerGuard = new FailedHandlerGuard();
diff --git a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
index b1651a44472..518c40bd4af 100644
--- a/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
+++ b/testutil-server/src/test/java/io/spine/testing/server/blackbox/BlackBoxTest.java
@@ -606,7 +606,7 @@ private Set<TypeName> toTypes(Iterable<Repository<?, ?>> repos) {
     }
 
     @Nested
-    @DisplayName("clreate an instance using passed components")
+    @DisplayName("create an instance using passed components")
     class CreateWith {
 
         @Test
@@ -863,7 +863,7 @@ void linkedToTheContextUnderTest() {
             assertThat(clientRequest.run(BbProjectView.query().build()))
                     .hasSize(0);
 
-            // Let's send a command with each of APIs.
+            // Let's send a command with each of the APIs.
             clientRequest.command(Given.createProject()).postAndForget();
             context().receivesCommand(Given.createProject());
 

From 4e92e172544f6ea7320ef345d1476ecacb163257 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 15:42:12 +0000
Subject: [PATCH 28/32] Address review comments in the docs

---
 .../src/main/java/io/spine/server/BoundedContext.java |  4 ++--
 server/src/main/java/io/spine/server/bus/Bus.java     |  4 ++--
 .../io/spine/server/bus/DelegatingDispatcher.java     |  2 +-
 .../java/io/spine/server/bus/DispatcherDelegate.java  | 11 ++++++++---
 .../java/io/spine/server/bus/MessageDispatcher.java   |  2 +-
 .../java/io/spine/server/stand/EventRegistry.java     |  5 +++++
 .../io/spine/server/transport/MessageChannel.java     |  5 +++++
 .../java/io/spine/system/server/SystemContext.java    |  2 +-
 .../test/java/io/spine/server/BoundedContextSpec.kt   |  4 ++--
 9 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/server/src/main/java/io/spine/server/BoundedContext.java b/server/src/main/java/io/spine/server/BoundedContext.java
index 5b0b53f9d1b..34d982ee981 100644
--- a/server/src/main/java/io/spine/server/BoundedContext.java
+++ b/server/src/main/java/io/spine/server/BoundedContext.java
@@ -638,12 +638,12 @@ public int hashCode() {
     public interface Probe extends ContextAware {
 
         /**
-         * The listener of commands posted processed by the context.
+         * The listener of commands processed by the context.
          */
         Listener<CommandEnvelope> commandListener();
 
         /**
-         * The listener of events posted processed by the context.
+         * The listener of events processed by the context.
          */
         Listener<EventEnvelope> eventListener();
 
diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 344f65de062..19af0625301 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -62,7 +62,7 @@
  * @param <D> the type of dispatches used by this bus
  */
 @Internal
-@SuppressWarnings("ClassWithTooManyMethods") // OK the abstract bus.
+@SuppressWarnings("ClassWithTooManyMethods") // OK for the abstract bus.
 public abstract class Bus<T extends Signal<?, ?, ?>,
                           E extends SignalEnvelope<?, T, ?>,
                           C extends MessageClass<? extends Message>,
@@ -103,7 +103,7 @@ public void register(D dispatcher) {
     }
 
     /**
-     * Stops dispatching messages the given dispatcher.
+     * Stops dispatching messages using the given dispatcher.
      *
      * @param dispatcher the dispatcher to unregister
      */
diff --git a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
index 3cc997c6681..5c524851ff0 100644
--- a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
+++ b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
@@ -31,7 +31,7 @@
 import io.spine.type.MessageClass;
 
 /**
- * A dispatcher which delegates the responsibilities to an aggregated {@link DispatcherDelegate}.
+ * A dispatcher which delegates the responsibilities to a {@link DispatcherDelegate}.
  *
  * @param <C>
  *         the type of the message class
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
index 4c550b4ae52..fefadc4f679 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
@@ -36,10 +36,15 @@
  *         the type of the dispatched message class
  * @param <E>
  *         the type of the message envelope
- * @apiNote The generic parameters are the same as the ones of the {@link DelegatingDispatcher}
- *      to which this delegate belongs. Even though they are not used in this interface directly,
+ * @apiNote
+ *      This interface does not extend {@link MessageDispatcher} in order to allow implementing
+ *      "native" dispatching interface and this delegation interface in one class.
+ *
+ *      <p>The generic parameters are the same as the ones of {@link MessageDispatcher} and
+ *      a {@link DelegatingDispatcher} to which this delegate belongs.
+ *      Even though they are not used in this interface directly,
  *      they bring semantic meaning to the interface and code clarity at the usage sites.
  */
-@SuppressWarnings("unused")
+@SuppressWarnings("unused") // see the API note above.
 public interface DispatcherDelegate<C extends MessageClass<?>, E extends MessageEnvelope<?, ?, ?>> {
 }
diff --git a/server/src/main/java/io/spine/server/bus/MessageDispatcher.java b/server/src/main/java/io/spine/server/bus/MessageDispatcher.java
index 67a05059f7d..ddbeb05612c 100644
--- a/server/src/main/java/io/spine/server/bus/MessageDispatcher.java
+++ b/server/src/main/java/io/spine/server/bus/MessageDispatcher.java
@@ -35,7 +35,7 @@
  * A dispatcher of a message.
  *
  * @param <C>
- *         the type of class of the dispatched messages
+ *         the type of message class of dispatched messages
  * @param <E>
  *         the type of the message envelopes
  */
diff --git a/server/src/main/java/io/spine/server/stand/EventRegistry.java b/server/src/main/java/io/spine/server/stand/EventRegistry.java
index d391197326a..21e1bc14746 100644
--- a/server/src/main/java/io/spine/server/stand/EventRegistry.java
+++ b/server/src/main/java/io/spine/server/stand/EventRegistry.java
@@ -62,6 +62,11 @@ interface EventRegistry extends AutoCloseable {
      */
     ImmutableSet<EventClass> eventClasses();
 
+    /**
+     * {@inheritDoc}
+     *
+     * <p>Overrides to remove the checked exception from the signature.
+     */
     @Override
     void close();
 }
diff --git a/server/src/main/java/io/spine/server/transport/MessageChannel.java b/server/src/main/java/io/spine/server/transport/MessageChannel.java
index ef80af072f5..cae94588aff 100644
--- a/server/src/main/java/io/spine/server/transport/MessageChannel.java
+++ b/server/src/main/java/io/spine/server/transport/MessageChannel.java
@@ -69,6 +69,11 @@ static ChannelId channelIdFor(TypeUrl messageType) {
         return channelId;
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * <p>Overrides to remove the checked exception from the signature.
+     */
     @Override
     void close();
 }
diff --git a/server/src/main/java/io/spine/system/server/SystemContext.java b/server/src/main/java/io/spine/system/server/SystemContext.java
index bb444bf3b14..03ba77aca47 100644
--- a/server/src/main/java/io/spine/system/server/SystemContext.java
+++ b/server/src/main/java/io/spine/system/server/SystemContext.java
@@ -108,7 +108,7 @@ public SystemClient createClient() {
     /**
      * {@inheritDoc}
      *
-     * <p>Since a system-bounded context does not have an associated system bounded context,
+     * <p>Since the System context does not have an associated System context of its own,
      * the method returns a {@link NoOpSystemWriteSide} instance.
      */
     @Override
diff --git a/server/src/test/java/io/spine/server/BoundedContextSpec.kt b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
index e18f52bf225..092ccb87bbc 100644
--- a/server/src/test/java/io/spine/server/BoundedContextSpec.kt
+++ b/server/src/test/java/io/spine/server/BoundedContextSpec.kt
@@ -175,7 +175,7 @@ internal class BoundedContextSpec {
     }
 
     @Nested
-    @DisplayName("provide internal secured access to")
+    @DisplayName("provide guarded internal access to")
     inner class InternalAccess {
 
         private lateinit var access: BoundedContext.InternalAccess
@@ -514,7 +514,7 @@ internal class BoundedContextSpec {
 
     @Nested
     @DisplayName("support diagnostics via `Probe`")
-    inner class SupportProbe {
+    inner class SupportBlackboxProbe {
 
         private val probe: BoundedContext.Probe = EmptyProbe()
 

From 01b815f5bc17d310f28879655268e37ab66325ae Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 15:46:41 +0000
Subject: [PATCH 29/32] Update dependency reports

---
 license-report.md | 24 ++++++++++++------------
 pom.xml           |  2 +-
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/license-report.md b/license-report.md
index 1bf9e5116ad..da6e689c6df 100644
--- a/license-report.md
+++ b/license-report.md
@@ -1,6 +1,6 @@
 
 
-# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -798,12 +798,12 @@
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:13 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Nov 01 15:46:08 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine:spine-core:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine:spine-core:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -1561,12 +1561,12 @@ This report was generated on **Tue Oct 31 23:41:13 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Nov 01 15:46:08 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine:spine-server:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine:spine-server:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -2372,12 +2372,12 @@ This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Nov 01 15:46:09 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-client:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine.tools:spine-testutil-client:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -3303,12 +3303,12 @@ This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Nov 01 15:46:09 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-core:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine.tools:spine-testutil-core:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -4234,12 +4234,12 @@ This report was generated on **Tue Oct 31 23:41:14 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:15 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Nov 01 15:46:10 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
 
-# Dependencies of `io.spine.tools:spine-testutil-server:2.0.0-SNAPSHOT.161`
+# Dependencies of `io.spine.tools:spine-testutil-server:2.0.0-SNAPSHOT.170`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -5213,4 +5213,4 @@ This report was generated on **Tue Oct 31 23:41:15 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
-This report was generated on **Tue Oct 31 23:41:15 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
+This report was generated on **Wed Nov 01 15:46:10 WET 2023** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index 6b4a78f8508..db7a8121183 100644
--- a/pom.xml
+++ b/pom.xml
@@ -62,7 +62,7 @@ all modules and does not describe the project structure per-subproject.
   <dependency>
     <groupId>io.spine</groupId>
     <artifactId>spine-base</artifactId>
-    <version>2.0.0-SNAPSHOT.190</version>
+    <version>2.0.0-SNAPSHOT.191</version>
     <scope>compile</scope>
   </dependency>
   <dependency>

From 0a665f69cdb70bdd503812dcaba99c314a8df1e7 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 17:12:41 +0000
Subject: [PATCH 30/32] Improve documentation

---
 server/src/main/java/io/spine/server/bus/Bus.java    |  4 ++--
 .../io/spine/server/bus/DelegatingDispatcher.java    |  3 ++-
 .../java/io/spine/server/bus/DispatcherDelegate.java |  6 ++++++
 .../server/commandbus/CommandDispatcherDelegate.java |  8 ++++----
 .../commandbus/DelegatingCommandDispatcher.java      |  4 ++--
 .../spine/server/event/EventDispatcherDelegate.java  | 12 ++++++++----
 6 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/server/src/main/java/io/spine/server/bus/Bus.java b/server/src/main/java/io/spine/server/bus/Bus.java
index 19af0625301..b7b2771dd15 100644
--- a/server/src/main/java/io/spine/server/bus/Bus.java
+++ b/server/src/main/java/io/spine/server/bus/Bus.java
@@ -121,7 +121,7 @@ public void unregister(DispatcherDelegate<C, E> delegate) {
     }
 
     /**
-     * Adds the passed listener to the bus.
+     * Adds the given listener to the bus.
      */
     public void add(Listener<E> listener) {
         checkNotNull(listener);
@@ -129,7 +129,7 @@ public void add(Listener<E> listener) {
     }
 
     /**
-     * Removes the passed listener from the bus.
+     * Removes the given listener from the bus.
      */
     public void remove(Listener<E> listener) {
         checkNotNull(listener);
diff --git a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
index 5c524851ff0..118158e68d9 100644
--- a/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
+++ b/server/src/main/java/io/spine/server/bus/DelegatingDispatcher.java
@@ -31,12 +31,13 @@
 import io.spine.type.MessageClass;
 
 /**
- * A dispatcher which delegates the responsibilities to a {@link DispatcherDelegate}.
+ * A dispatcher which passes the responsibilities to its {@linkplain #delegate() delegate}.
  *
  * @param <C>
  *         the type of the message class
  * @param <E>
  *         the type of the message envelope
+ * @see DispatcherDelegate
  */
 @Internal
 public interface DelegatingDispatcher<C extends MessageClass<?>,
diff --git a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
index fefadc4f679..1f10177f3d1 100644
--- a/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/bus/DispatcherDelegate.java
@@ -32,6 +32,11 @@
 /**
  * A delegate of a {@link DelegatingDispatcher}.
  *
+ * <p>This is a common interface for objects which need to dispatch messages of
+ * one kind (e.g., events), but are unable to implement {@link MessageDispatcher} because
+ * they already implement this interface with generic parameters for another
+ * kind of messages (e.g., commands).
+ *
  * @param <C>
  *         the type of the dispatched message class
  * @param <E>
@@ -44,6 +49,7 @@
  *      a {@link DelegatingDispatcher} to which this delegate belongs.
  *      Even though they are not used in this interface directly,
  *      they bring semantic meaning to the interface and code clarity at the usage sites.
+ * @see DelegatingDispatcher
  */
 @SuppressWarnings("unused") // see the API note above.
 public interface DispatcherDelegate<C extends MessageClass<?>, E extends MessageEnvelope<?, ?, ?>> {
diff --git a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
index 2fb22dd56c7..bb9fb59df66 100644
--- a/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/commandbus/CommandDispatcherDelegate.java
@@ -38,18 +38,18 @@
  * the {@link io.spine.server.commandbus.CommandDispatcher CommandDispatcher}.
  *
  * <p>A typical example of a {@code CommandDispatcherDelegate} usage is a routine, which
- * simultaneously dispatches different types of {@linkplain com.google.protobuf.Message messages}
- * in addition to {@code Command}s.
+ * simultaneously dispatches different types of messages (e.g., {@code Event}s) in addition
+ * to {@code Command}s.
  *
  * <p>In this case such a class would have to implement several
  * {@link io.spine.server.bus.MessageDispatcher MessageDispatcher} child interfaces
  * (such as {@link io.spine.server.commandbus.CommandDispatcher CommandDispatcher} or
  * {@link io.spine.server.event.EventDispatcher EventDispatcher}). However, it is impossible
  * to implement the same {@link io.spine.server.bus.MessageDispatcher#messageClasses()
- * getMessageClasses()} method several times with the different types of {@code MessageClass}es
+ * messageClasses()} method several times with the different types of {@code MessageClass}es
  * returned.
  *
- * <p>The same interference takes place in attempt to implement
+ * <p>The same interference takes place in an attempt to implement
  * {@link io.spine.server.bus.UnicastDispatcher#dispatch(io.spine.server.type.MessageEnvelope)
  * UnicastDispatcher.dispatch(MessageEnvelope)} method with the different types of
  * {@code MessageEnvelope}s dispatches simultaneously.
diff --git a/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java b/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
index 50e1829ffe5..5b6e32ce512 100644
--- a/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
+++ b/server/src/main/java/io/spine/server/commandbus/DelegatingCommandDispatcher.java
@@ -34,8 +34,8 @@
 import io.spine.server.type.CommandEnvelope;
 
 /**
- * A {@link CommandDispatcher}, that delegates the responsibilities to an aggregated
- * {@linkplain CommandDispatcherDelegate delegate instance}.
+ * A dispatcher of commands which delegates the responsibilities to
+ * a {@link CommandDispatcherDelegate}.
  *
  * @see CommandDispatcherDelegate
  */
diff --git a/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java b/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
index ad6b8fcacae..bd613d56b7e 100644
--- a/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
+++ b/server/src/main/java/io/spine/server/event/EventDispatcherDelegate.java
@@ -37,10 +37,14 @@
  * A common interface for objects which need to dispatch {@linkplain io.spine.core.Event events},
  * but are unable to implement {@link io.spine.server.event.EventDispatcher EventDispatcher}.
  *
- * <p>This interface defines own contract (instead of extending {@link
- * io.spine.server.bus.MessageDispatcher MessageDispatcher} to allow classes that dispatch
- * messages other than events (by implementing {@link io.spine.server.bus.MessageDispatcher
- * MessageDispatcher}), and dispatch events by implementing this interface.
+ * <p>This interface defines own contract for dispatching events, instead of extending
+ * the {@link io.spine.server.bus.MessageDispatcher MessageDispatcher} interface.
+ * Such an arrangement allows classes that dispatch messages other than events
+ * (by implementing {@link io.spine.server.bus.MessageDispatcher MessageDispatcher}), also
+ * dispatch events by implementing <em>this</em> interface.
+ *
+ * <p>Also this interface provides separate methods for obtaining
+ * {@linkplain #domesticEvents() domestic} and {@linkplain #externalEvents() external} event types.
  *
  * @see DelegatingEventDispatcher
  */

From ea90a4640f57120b524101e2feeebc7bd5788e79 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 18:36:50 +0000
Subject: [PATCH 31/32] Update dependencies of Windows build workflow

---
 .github/workflows/build-on-windows.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build-on-windows.yml b/.github/workflows/build-on-windows.yml
index c910b2009fe..47fefa69164 100644
--- a/.github/workflows/build-on-windows.yml
+++ b/.github/workflows/build-on-windows.yml
@@ -17,9 +17,9 @@ jobs:
           java-version: 11
           distribution: zulu
           cache: gradle
-
+      # See: https://github.com/al-cheb/configure-pagefile-action
       - name: Configure Pagefile
-        uses: al-cheb/configure-pagefile-action@v1.2
+        uses: al-cheb/configure-pagefile-action@v1.3
 
       - name: Build project and run tests
         shell: cmd
@@ -28,7 +28,7 @@ jobs:
 
       # See: https://github.com/marketplace/actions/junit-report-action
       - name: Publish Test Report
-        uses: mikepenz/action-junit-report@v3.7.6
+        uses: mikepenz/action-junit-report@v4.0.3
         if: always() # always run even if the previous step fails
         with:
           report_paths: '**/build/test-results/**/TEST-*.xml'

From 43937de6ff122fa8aa8108404c35a249ff019fb0 Mon Sep 17 00:00:00 2001
From: alexander-yevsyukov <alexander.yevsyukov@teamdev.com>
Date: Wed, 1 Nov 2023 18:37:28 +0000
Subject: [PATCH 32/32] Update dependency of Ubuntu build workflow

---
 .github/workflows/build-on-ubuntu.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build-on-ubuntu.yml b/.github/workflows/build-on-ubuntu.yml
index 788b891736b..55bb482f644 100644
--- a/.github/workflows/build-on-ubuntu.yml
+++ b/.github/workflows/build-on-ubuntu.yml
@@ -24,7 +24,7 @@ jobs:
 
       # See: https://github.com/marketplace/actions/junit-report-action
       - name: Publish Test Report
-        uses: mikepenz/action-junit-report@v3.7.6
+        uses: mikepenz/action-junit-report@v4.0.3
         if: always() # always run even if the previous step fails
         with:
           report_paths: '**/build/test-results/**/TEST-*.xml'