Merge pull request #1542 from SpineEventEngine/relax-policy-whenever-…

…back Make `whenever()` return `Iterable<Message>` again
SpineEventEngine · Nov 3, 2023 · 4a61ccc · 4a61ccc
2 parents 3b74ac8 + 3109413
commit 4a61ccc
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diff --git a/license-report.md b/license-report.md
@@ -1,6 +1,6 @@
 
 
-# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.170`
+# Dependencies of `io.spine:spine-client:2.0.0-SNAPSHOT.171`
 
 ## 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 **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).
+This report was generated on **Fri Nov 03 00:38:26 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.170`
+# Dependencies of `io.spine:spine-core:2.0.0-SNAPSHOT.171`
 
 ## Runtime
 1.  **Group** : com.google.code.findbugs. **Name** : jsr305. **Version** : 3.0.2.
@@ -1561,12 +1561,12 @@ This report was generated on **Wed Nov 01 15:46:08 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly 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).
+This report was generated on **Fri Nov 03 00:38:27 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.170`
+# Dependencies of `io.spine:spine-server:2.0.0-SNAPSHOT.171`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -2372,12 +2372,12 @@ This report was generated on **Wed Nov 01 15:46:08 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly 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).
+This report was generated on **Fri Nov 03 00:38:27 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.170`
+# Dependencies of `io.spine.tools:spine-testutil-client:2.0.0-SNAPSHOT.171`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -3303,12 +3303,12 @@ This report was generated on **Wed Nov 01 15:46:09 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly 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).
+This report was generated on **Fri Nov 03 00:38:28 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.170`
+# Dependencies of `io.spine.tools:spine-testutil-core:2.0.0-SNAPSHOT.171`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -4234,12 +4234,12 @@ This report was generated on **Wed Nov 01 15:46:09 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly 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).
+This report was generated on **Fri Nov 03 00:38:28 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.170`
+# Dependencies of `io.spine.tools:spine-testutil-server:2.0.0-SNAPSHOT.171`
 
 ## Runtime
 1.  **Group** : com.google.android. **Name** : annotations. **Version** : 4.1.1.4.
@@ -5213,4 +5213,4 @@ This report was generated on **Wed Nov 01 15:46:10 WET 2023** using [Gradle-Lice
 
 The dependencies distributed under several licenses, are used according their commercial-use-friendly 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).
+This report was generated on **Fri Nov 03 00:38:29 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).
diff --git 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.170</version>
+<version>2.0.0-SNAPSHOT.171</version>
 
 <inceptionYear>2015</inceptionYear>
 

diff --git a/server/src/main/java/io/spine/server/tuple/Either.java b/server/src/main/java/io/spine/server/tuple/Either.java
@@ -52,7 +52,7 @@ public abstract class Either implements Iterable<Message>, Serializable {
     protected Either(Message value, int index) {
         /* We need instances of GeneratedMessageV3 as they are Serializable.
            The only known case of message class which does not descend from
-           GeneratedMessageV3 is DynamicMessage, and  Spine does not support it. */
+           GeneratedMessageV3 is DynamicMessage, and Spine SDK does not support it. */
         this.value = (GeneratedMessageV3) checkNotNull(value);
         checkArgument(index >= 0, "Index must be greater or equal zero");
         this.index = index;

diff --git a/server/src/main/java/io/spine/server/tuple/Element.java b/server/src/main/java/io/spine/server/tuple/Element.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.
@@ -30,6 +30,7 @@
 import com.google.protobuf.GeneratedMessageV3;
 import com.google.protobuf.Message;
 import io.spine.base.EventMessage;
+import io.spine.server.model.Nothing;
 
 import java.io.IOException;
 import java.io.ObjectInputStream;
@@ -67,7 +68,11 @@ final class Element implements Serializable {
             this.type = Type.OPTIONAL;
         } else if (value instanceof GeneratedMessageV3) {
             var messageV3 = (GeneratedMessageV3) value;
-            checkNotDefault(messageV3);
+            // Treat `Nothing` as a special case, allowing its default instance
+            // so that `Just<Nothing>` is possible.
+            if (!(value instanceof Nothing)) {
+                checkNotDefault(messageV3);
+            }
             this.type = Type.MESSAGE;
         } else {
             throw newIllegalArgumentException(
@@ -82,7 +87,7 @@ final class Element implements Serializable {
      * Obtains the value of the element by its index and casts it to the type {@code <T>}.
      */
     @SuppressWarnings("TypeParameterUnusedInFormals") // See Javadoc.
-    static <T> T value(Tuple tuple, IndexOf index) {
+    static <M extends Message, T> T value(Tuple tuple, IndexOf index) {
         @SuppressWarnings("unchecked") // The caller is responsible for the correct type.
         var value = (T) tuple.get(index.value());
         return value;

diff --git a/server/src/main/java/io/spine/server/tuple/Pair.java b/server/src/main/java/io/spine/server/tuple/Pair.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.
@@ -36,7 +36,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static io.spine.server.tuple.Element.value;
-import static io.spine.server.tuple.Values.isOptionalPresent;
 import static java.util.Optional.ofNullable;
 
 /**

diff --git a/server/src/main/java/io/spine/server/tuple/Quartet.java b/server/src/main/java/io/spine/server/tuple/Quartet.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.
@@ -37,7 +37,6 @@
 import java.util.Optional;
 
 import static io.spine.server.tuple.Element.value;
-import static io.spine.server.tuple.Values.isOptionalPresent;
 import static java.util.Optional.ofNullable;
 
 /**
@@ -170,13 +169,13 @@ private static <M extends Message> M checkNotNullOrEmpty(M value) {
         return checkNotEmpty(Quartet.class, value);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotNullOrEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotNullOrEmpty(M... values) {
         checkAllNotNullOrEmpty(Quartet.class, values);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotEmpty(M... values) {
         checkAllNotEmpty(Quartet.class, values);
     }
 }
diff --git a/server/src/main/java/io/spine/server/tuple/Quintet.java b/server/src/main/java/io/spine/server/tuple/Quintet.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.
@@ -38,7 +38,6 @@
 import java.util.Optional;
 
 import static io.spine.server.tuple.Element.value;
-import static io.spine.server.tuple.Values.isOptionalPresent;
 import static java.util.Optional.ofNullable;
 
 /**
@@ -62,8 +61,8 @@
  *         the type of the fifth element
  */
 public final class Quintet<A extends Message, B, C, D, E>
-    extends Tuple
-    implements AValue<A>, BValue<B>, CValue<C>, DValue<D>, EValue<E> {
+        extends Tuple
+        implements AValue<A>, BValue<B>, CValue<C>, DValue<D>, EValue<E> {
 
     private static final long serialVersionUID = 0L;
 
@@ -203,13 +202,13 @@ private static <M extends Message> M checkNotNullOrEmpty(M value) {
         return checkNotEmpty(Quintet.class, value);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotNullOrEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotNullOrEmpty(M... values) {
         checkAllNotNullOrEmpty(Quintet.class, values);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotEmpty(M... values) {
         checkAllNotEmpty(Quintet.class, values);
     }
 }
diff --git a/server/src/main/java/io/spine/server/tuple/Triplet.java b/server/src/main/java/io/spine/server/tuple/Triplet.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.
@@ -36,7 +36,6 @@
 import java.util.Optional;
 
 import static io.spine.server.tuple.Element.value;
-import static io.spine.server.tuple.Values.isOptionalPresent;
 import static java.util.Optional.ofNullable;
 
 /**
@@ -144,13 +143,13 @@ private static <M extends Message> M checkNotNullOrEmpty(M value) {
         return checkNotEmpty(Triplet.class, value);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotNullOrEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotNullOrEmpty(M... values) {
         checkAllNotNullOrEmpty(Triplet.class, values);
     }
 
-    @SuppressWarnings("OverloadedVarargsMethod") // to avoid repeated usage of this class name.
-    private static void checkAllNotEmpty(Message... values) {
+    @SafeVarargs
+    private static <M extends Message> void checkAllNotEmpty(M... values) {
         checkAllNotEmpty(Triplet.class, values);
     }
 }
diff --git a/server/src/main/java/io/spine/server/tuple/Tuple.java b/server/src/main/java/io/spine/server/tuple/Tuple.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.
@@ -107,15 +107,17 @@ M checkNotNullOrEmpty(Class<T> checkingClass, M value) {
         return result;
     }
 
-    static <T extends Tuple>
-    void checkAllNotNullOrEmpty(Class<T> checkingClass, Message... values) {
+    @SafeVarargs
+    static <M extends Message, T extends Tuple>
+    void checkAllNotNullOrEmpty(Class<T> checkingClass, M... values) {
         for (var value : values) {
             checkNotNullOrEmpty(checkingClass, value);
         }
     }
 
-    static <T extends Tuple>
-    void checkAllNotEmpty(Class<T> checkingClass, Message... values) {
+    @SafeVarargs
+    static <M extends Message, T extends Tuple>
+    void checkAllNotEmpty(Class<T> checkingClass, M... values) {
         for (var value : values) {
             checkNotEmpty(checkingClass, value);
         }
@@ -157,6 +159,20 @@ public final boolean equals(Object obj) {
         return Objects.equals(this.values, other.values);
     }
 
+    /**
+     * If the passed {@code value} is an {@code Optional}, tells if its value is present.
+     *
+     * <p>Otherwise, returns {@code true}.
+     */
+    static boolean isOptionalPresent(Object value) {
+        checkNotNull(value);
+        if(!(value instanceof Optional)) {
+            return true;
+        }
+        var asOptional = (Optional<?>) value;
+        return asOptional.isPresent();
+    }
+
     /**
      * Traverses through elements obtaining a message value from them.
      */

diff --git a/server/src/main/kotlin/io/spine/server/event/Just.kt b/server/src/main/kotlin/io/spine/server/event/Just.kt
@@ -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.
@@ -27,21 +27,31 @@
 package io.spine.server.event
 
 import io.spine.base.EventMessage
+import io.spine.server.model.Nothing
 import io.spine.server.tuple.Tuple
 
 /**
  * A tuple of one event.
  *
- * Used when returning an iterable from a handler method for better readability over `List<E>`.
+ * Used when returning an `Iterable` from a handler method for better readability over
+ * `Iterable<E>` or `List<E>`.
  *
  * @param E the type of the event.
  */
 public class Just<E : EventMessage>(event: E) : Tuple(event) {
 
     public companion object {
 
+        @Suppress("ConstPropertyName") // Following Java conventions.
         private const val serialVersionUID: Long = 0L
 
+        /**
+         * The instance of `Just<Nothing>`.
+         */
+        public val nothing: Just<Nothing> by lazy {
+            Just(Nothing.getDefaultInstance())
+        }
+
         /**
          * A factory method for Java.
          *
@@ -51,5 +61,13 @@ public class Just<E : EventMessage>(event: E) : Tuple(event) {
          */
         @JvmStatic
         public fun <E : EventMessage> just(event: E): Just<E> = Just(event)
+
+        /**
+         * Obtains the instance of `Just<Noting>` for Java code.
+         *
+         * Prefer the [nothing] property of the companion object in Kotlin.
+         */
+        @JvmStatic
+        public fun nothing(): Just<Nothing> = nothing
     }
 }