Adds the EventKey and EventKeyFactory. (opensearch-project#4627)

Adds the EventKey and EventKeyFactory. Resolves opensearch-project#1916.

Signed-off-by: David Venable <dlv@amazon.com>

data-prepper-api/src/main/java/org/opensearch/dataprepper/model/event/Event.java

@@ -26,6 +26,15 @@
  */
 public interface Event extends Serializable {
 
+    /**
+     * Adds or updates the key with a given value in the Event
+     *
+     * @param key where the value will be set
+     * @param value value to set the key to
+     * @since 2.8
+     */
+    void put(EventKey key, Object value);
+
     /**
      * Adds or updates the key with a given value in the Event
      *
@@ -35,6 +44,17 @@ public interface Event extends Serializable {
      */
     void put(String key, Object value);
 
+    /**
+     * Retrieves the given key from the Event
+     *
+     * @param key the value to retrieve from
+     * @param clazz the return type of the value
+     * @param <T> The type
+     * @return T a clazz object from the key
+     * @since 2.8
+     */
+    <T> T get(EventKey key, Class<T> clazz);
+
     /**
      * Retrieves the given key from the Event
      *
@@ -46,6 +66,17 @@ public interface Event extends Serializable {
      */
     <T> T get(String key, Class<T> clazz);
 
+    /**
+     * Retrieves the given key from the Event as a List
+     *
+     * @param key   the value to retrieve from
+     * @param clazz the return type of elements in the list
+     * @param <T>   The type
+     * @return {@literal List<T>} a list of clazz elements
+     * @since 2.8
+     */
+    <T> List<T> getList(EventKey key, Class<T> clazz);
+
     /**
      * Retrieves the given key from the Event as a List
      *
@@ -57,6 +88,14 @@ public interface Event extends Serializable {
      */
     <T> List<T> getList(String key, Class<T> clazz);
 
+    /**
+     * Deletes the given key from the Event
+     *
+     * @param key the field to be deleted
+     * @since 2.8
+     */
+    void delete(EventKey key);
+
     /**
      * Deletes the given key from the Event
      *
@@ -87,6 +126,15 @@ public interface Event extends Serializable {
      */
     JsonNode getJsonNode();
 
+    /**
+     * Gets a serialized Json string of the specific key in the Event
+     *
+     * @param key the field to be returned
+     * @return Json string of the field
+     * @since 2.8
+     */
+    String getAsJsonString(EventKey key);
+
     /**
      * Gets a serialized Json string of the specific key in the Event
      *
@@ -104,6 +152,15 @@ public interface Event extends Serializable {
      */
     EventMetadata getMetadata();
 
+    /**
+     * Checks if the key exists.
+     *
+     * @param key name of the key to look for
+     * @return returns true if the key exists, otherwise false
+     * @since 2.8
+     */
+    boolean containsKey(EventKey key);
+
     /**
      * Checks if the key exists.
      *
@@ -113,6 +170,15 @@ public interface Event extends Serializable {
      */
     boolean containsKey(String key);
 
+    /**
+     * Checks if the value stored for the key is list
+     *
+     * @param key name of the key to look for
+     * @return returns true if the key is a list, otherwise false
+     * @since 2.8
+     */
+    boolean isValueAList(EventKey key);
+
     /**
      * Checks if the value stored for the key is list
      *

data-prepper-api/src/main/java/org/opensearch/dataprepper/model/event/EventKey.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.dataprepper.model.event;
+
+/**
+ * Model class to represent a key into a Data Prepper {@link Event}.
+ *
+ * @since 2.9
+ */
+public interface EventKey {
+    /**
+     * The original key provided as a string.
+     *
+     * @return The key as a string
+     * @since 2.9
+     */
+    String getKey();
+}

data-prepper-api/src/main/java/org/opensearch/dataprepper/model/event/EventKeyFactory.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.dataprepper.model.event;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * A factory for producing {@link EventKey} objects.
+ *
+ * @since 2.9
+ */
+public interface EventKeyFactory {
+    /**
+     * Creates an {@link EventKey} with given actions.
+     *
+     * @param key The key
+     * @param forActions Actions to support
+     * @return The EventKey
+     * @since 2.9
+     */
+    EventKey createEventKey(String key, EventAction... forActions);
+
+    /**
+     * Creates an {@link EventKey} for the default actions, which are all.
+     *
+     * @param key The key
+     * @return The EventKey
+     * @since 2.9
+     */
+    default EventKey createEventKey(final String key) {
+        return createEventKey(key, EventAction.ALL);
+    }
+
+    /**
+     * An action on an Event.
+     *
+     * @since 2.9
+     */
+    enum EventAction {
+        GET,
+        DELETE,
+        PUT,
+        ALL(GET, DELETE, PUT);
+
+        private final List<EventAction> includedActions;
+
+        EventAction(EventAction... eventActions) {
+            includedActions = Arrays.asList(eventActions);
+
+        }
+
+        boolean isMutableAction() {
+            return this != GET;
+        }
+
+        Set<EventAction> getSupportedActions() {
+            final EnumSet<EventAction> supportedActions = EnumSet.noneOf(EventAction.class);
+            supportedActions.add(this);
+            supportedActions.addAll(includedActions);
+
+            return Collections.unmodifiableSet(supportedActions);
+        }
+    }
+}