Add @nullable annotations

Author: Milder Hernandez Cagua

agents/semantickernel-agents-core/src/main/java/com/microsoft/semantickernel/agents/chatcompletion/ChatCompletionAgent.java

@@ -62,7 +62,7 @@ private ChatCompletionAgent(
     @Override
     public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(
             List<ChatMessageContent<?>> messages,
-            AgentThread thread,
+            @Nullable AgentThread thread,
             @Nullable AgentInvokeOptions options
     ) {
         return ensureThreadExistsWithMessagesAsync(messages, thread, ChatHistoryAgentThread::new)

semantickernel-api/src/main/java/com/microsoft/semantickernel/agents/Agent.java

@@ -17,6 +17,8 @@
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import javax.annotation.Nullable;
+
 /**
  * Interface for a semantic kernel agent.
  */
@@ -49,7 +51,7 @@ public interface Agent {
      * @param message The message to process
      * @return A Mono containing the agent response
      */
-    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message);
+    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(@Nullable ChatMessageContent<?> message);
 
     /**
      * Invokes the agent with the given message and thread.
@@ -58,7 +60,8 @@ public interface Agent {
      * @param thread The agent thread to use
      * @return A Mono containing the agent response
      */
-    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message, AgentThread thread);
+    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(@Nullable ChatMessageContent<?> message,
+                                                                     @Nullable AgentThread thread);
 
     /**
      * Invokes the agent with the given message, thread, and options.
@@ -68,7 +71,9 @@ public interface Agent {
      * @param options The options for invoking the agent
      * @return A Mono containing the agent response
      */
-    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message, AgentThread thread, AgentInvokeOptions options);
+    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(@Nullable ChatMessageContent<?> message,
+                                                                     @Nullable AgentThread thread,
+                                                                     @Nullable AgentInvokeOptions options);
 
     /**
      * Invoke the agent with the given chat history.
@@ -78,7 +83,9 @@ public interface Agent {
      * @param options The options for invoking the agent
      * @return A Mono containing the agent response
      */
-    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(List<ChatMessageContent<?>> messages, AgentThread thread, AgentInvokeOptions options);
+    Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(List<ChatMessageContent<?>> messages,
+                                                                     @Nullable AgentThread thread,
+                                                                     @Nullable AgentInvokeOptions options);
 
     /**
      * Notifies the agent of a new message.

semantickernel-api/src/main/java/com/microsoft/semantickernel/agents/KernelAgent.java

@@ -11,6 +11,7 @@
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
+import javax.annotation.Nullable;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -169,19 +170,25 @@ protected <T extends AgentThread> Mono<T> ensureThreadExistsWithMessagesAsync(Li
     }
 
     @Override
-    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message) {
-        return invokeAsync(message, null);
+    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(@Nullable ChatMessageContent<?> message) {
+        return invokeAsync(message, null, null);
     }
 
     @Override
-    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message, AgentThread thread) {
-        return invokeAsync(message, thread, AgentInvokeOptions.builder().build());
+    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(@Nullable ChatMessageContent<?> message,
+                                                                            @Nullable AgentThread thread) {
+        return invokeAsync(message, thread, null);
     }
 
     @Override
-    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(ChatMessageContent<?> message, AgentThread thread, AgentInvokeOptions options) {
+    public Mono<List<AgentResponseItem<ChatMessageContent<?>>>> invokeAsync(
+            @Nullable ChatMessageContent<?> message,
+            @Nullable AgentThread thread,
+            @Nullable AgentInvokeOptions options) {
         ArrayList<ChatMessageContent<?>> messages = new ArrayList<>();
-        messages.add(message);
+        if (message != null) {
+            messages.add(message);
+        }
         return invokeAsync(messages, thread, options);
     }
 }