Java: feat(): add PostChatCompletionEvent (#5342)

### Motivation and Context

Fix：https://github.com/microsoft/semantic-kernel/issues/5314

### Description

After the Chat Completion, triggered an PostChatCompletionEvent.

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

---------

Co-authored-by: gaozhirong <[email protected]>

java/aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/chatcompletion/OpenAIChatCompletion.java

@@ -25,6 +25,7 @@ import com.microsoft.semantickernel.contextvariables.ContextVariableTypes;
 import com.microsoft.semantickernel.exceptions.AIException;
 import com.microsoft.semantickernel.exceptions.SKException;
 import com.microsoft.semantickernel.hooks.KernelHooks;
+import com.microsoft.semantickernel.hooks.PostChatCompletionEvent;
 import com.microsoft.semantickernel.hooks.PreChatCompletionEvent;
 import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.FunctionResultMetadata;
@@ -154,6 +155,9 @@ public class OpenAIChatCompletion implements ChatCompletionService {
                     .filter(Objects::nonNull)
                     .collect(Collectors.toList());
 
+                // execute post chat completion hook
+                kernelHooks.executeHooks(new PostChatCompletionEvent(completions));
+
                 // Just return the result:
                 // If we don't want to attempt to invoke any functions
                 // Or if we are auto-invoking, but we somehow end up with other than 1 choice even though only 1 was requested

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example57_KernelHooks.java

@@ -19,6 +19,7 @@ import com.microsoft.semantickernel.hooks.KernelHook.PreChatCompletionHook;
 import com.microsoft.semantickernel.hooks.KernelHook.PromptRenderedHook;
 import com.microsoft.semantickernel.hooks.KernelHook.PromptRenderingHook;
 import com.microsoft.semantickernel.hooks.KernelHooks;
+import com.microsoft.semantickernel.hooks.PostChatCompletionEvent;
 import com.microsoft.semantickernel.hooks.PreChatCompletionEvent;
 import com.microsoft.semantickernel.hooks.PromptRenderedEvent;
 import com.microsoft.semantickernel.orchestration.FunctionResult;
@@ -347,6 +348,12 @@ public class Example57_KernelHooks {
                 PreChatCompletionHook.cloneOptionsWithMessages(options, messages));
         });
 
+        kernel.getGlobalKernelHooks().addPostChatCompletionHook(event -> {
+            System.out.println("Chat completion");
+            System.out.println("Id: " + event.getChatCompletions().getId());
+            return event;
+        });
+
         try {
             // Invoke prompt to trigger execution hooks.
             var result = kernel.invokeAsync(writerFunction)

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/KernelHook.java

@@ -118,4 +118,17 @@ public interface KernelHook<T extends KernelHookEvent> extends Predicate<KernelH
             return PreChatCompletionEvent.class.isAssignableFrom(arguments.getClass());
         }
     }
+
+    /**
+     * A hook that accepts {@link PostChatCompletionEvent}
+     */
+    interface PostChatCompletionHook extends KernelHook<PostChatCompletionEvent> {
+
+        @Override
+        default boolean test(KernelHookEvent arguments) {
+            return PostChatCompletionEvent.class.isAssignableFrom(arguments.getClass());
+        }
+
+    }
+
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/KernelHooks.java

@@ -3,6 +3,7 @@ package com.microsoft.semantickernel.hooks;
 
 import com.microsoft.semantickernel.hooks.KernelHook.FunctionInvokedHook;
 import com.microsoft.semantickernel.hooks.KernelHook.FunctionInvokingHook;
+import com.microsoft.semantickernel.hooks.KernelHook.PostChatCompletionHook;
 import com.microsoft.semantickernel.hooks.KernelHook.PreChatCompletionHook;
 import com.microsoft.semantickernel.hooks.KernelHook.PromptRenderedHook;
 import com.microsoft.semantickernel.hooks.KernelHook.PromptRenderingHook;
@@ -101,6 +102,17 @@ public class KernelHooks {
         return addHook((PreChatCompletionHook) function::apply);
     }
 
+    /**
+     * Add a {@link PostChatCompletionEvent} to the collection of hooks.
+     *
+     * @param function the function to add
+     * @return the key of the hook in the collection
+     */
+    public String addPostChatCompletionHook(
+        Function<PostChatCompletionEvent, PostChatCompletionEvent> function) {
+        return addHook((PostChatCompletionHook) function::apply);
+    }
+
     /**
      * Add a {@link PromptRenderedHook} to the collection of hooks.
      *
@@ -227,6 +239,12 @@ public class KernelHooks {
             throw new UnsupportedOperationException("unmodifiable instance of KernelHooks");
         }
 
+        @Override
+        public String addPostChatCompletionHook(
+            Function<PostChatCompletionEvent, PostChatCompletionEvent> function) {
+            throw new UnsupportedOperationException("unmodifiable instance of KernelHooks");
+        }
+
         @Override
         public String addPromptRenderedHook(
             Function<PromptRenderedEvent, PromptRenderedEvent> function) {

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/PostChatCompletionEvent.java

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft. All rights reserved.
+package com.microsoft.semantickernel.hooks;
+
+import com.azure.ai.openai.models.ChatCompletions;
+
+/**
+ * Represents a KernelHookEvent that is raised after a chat completion is invoked.
+ */
+public class PostChatCompletionEvent implements KernelHookEvent {
+
+    private final ChatCompletions chatCompletions;
+
+    /**
+     * Creates a new instance of the {@link PostChatCompletionEvent} class.
+     *
+     * @param chatCompletions the chat completions
+     */
+    public PostChatCompletionEvent(ChatCompletions chatCompletions) {
+        this.chatCompletions = chatCompletions;
+    }
+
+    /**
+     * Gets the chat completions.
+     *
+     * @return the chat completions
+     */
+    public ChatCompletions getChatCompletions() {
+        return chatCompletions;
+    }
+}