Add additional FunctionChoiceBehavior creators and Nullables

semantickernel-api/src/main/java/com/microsoft/semantickernel/functionchoice/FunctionChoiceBehavior.java

@@ -66,6 +66,22 @@ public static FunctionChoiceBehavior auto(boolean autoInvoke) {
         return new AutoFunctionChoiceBehavior(autoInvoke, null, null);
     }
 
+    /**
+     * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
+     *
+     * @param autoInvoke Enable or disable auto-invocation.
+     *                   If auto-invocation is enabled, the model may request that the Semantic Kernel
+     *                   invoke the kernel functions and return the value to the model.
+     * @param functions Functions to provide to the model. If null, all the Kernel's plugins' functions are provided to the model.
+     *                  If empty, no functions are provided to the model, which is equivalent to disabling function calling.
+     *
+     * @return A new FunctionChoiceBehavior instance with all kernel functions allowed.
+     */
+    public static FunctionChoiceBehavior auto(boolean autoInvoke,
+                                              @Nullable List<KernelFunction<?>> functions) {
+        return new AutoFunctionChoiceBehavior(autoInvoke, functions, null);
+    }
+
     /**
      * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
      *
@@ -79,11 +95,25 @@ public static FunctionChoiceBehavior auto(boolean autoInvoke) {
      * @return A new FunctionChoiceBehavior instance with all kernel functions allowed.
      */
     public static FunctionChoiceBehavior auto(boolean autoInvoke,
-        List<KernelFunction<?>> functions,
-        @Nullable FunctionChoiceBehaviorOptions options) {
+                                              @Nullable List<KernelFunction<?>> functions,
+                                              @Nullable FunctionChoiceBehaviorOptions options) {
         return new AutoFunctionChoiceBehavior(autoInvoke, functions, options);
     }
 
+    /**
+     * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
+     * <p>
+     * This behavior forces the model to call the provided functions.
+     * SK connectors will invoke a requested function or multiple requested functions if the model requests multiple ones in one request,
+     * while handling the first request, and stop advertising the functions for the following requests to prevent the model from repeatedly calling the same function(s).
+     *
+     * @return A new FunctionChoiceBehavior instance with the required function.
+     */
+    public static FunctionChoiceBehavior required(boolean autoInvoke,
+                                                  @Nullable List<KernelFunction<?>> functions) {
+        return new RequiredFunctionChoiceBehavior(autoInvoke, functions, null);
+    }
+
     /**
      * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
      * <p>
@@ -96,11 +126,20 @@ public static FunctionChoiceBehavior auto(boolean autoInvoke,
      * @return A new FunctionChoiceBehavior instance with the required function.
      */
     public static FunctionChoiceBehavior required(boolean autoInvoke,
-        List<KernelFunction<?>> functions,
-        @Nullable FunctionChoiceBehaviorOptions options) {
+                                                  @Nullable List<KernelFunction<?>> functions,
+                                                  @Nullable FunctionChoiceBehaviorOptions options) {
         return new RequiredFunctionChoiceBehavior(autoInvoke, functions, options);
     }
 
+    /**
+     * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
+     * <p>
+     * This behavior is useful if the user should first validate what functions the model will use.
+     */
+    public static FunctionChoiceBehavior none() {
+        return new NoneFunctionChoiceBehavior(null, null);
+    }
+
     /**
      * Gets an instance of the FunctionChoiceBehavior that provides either all the Kernel's plugins functions to the AI model to call or specific functions.
      * <p>
@@ -109,7 +148,7 @@ public static FunctionChoiceBehavior required(boolean autoInvoke,
      * @param functions Functions to provide to the model. If null, all the Kernel's plugins' functions are provided to the model.
      *                  If empty, no functions are provided to the model, which is equivalent to disabling function calling.
      */
-    public static FunctionChoiceBehavior none(List<KernelFunction<?>> functions,
+    public static FunctionChoiceBehavior none(@Nullable List<KernelFunction<?>> functions,
         @Nullable FunctionChoiceBehaviorOptions options) {
         return new NoneFunctionChoiceBehavior(functions, options);
     }

semantickernel-api/src/main/java/com/microsoft/semantickernel/functionchoice/NoneFunctionChoiceBehavior.java

@@ -3,15 +3,16 @@
 
 import com.microsoft.semantickernel.semanticfunctions.KernelFunction;
 
+import javax.annotation.Nullable;
 import java.util.List;
 
 public class NoneFunctionChoiceBehavior extends FunctionChoiceBehavior {
 
     /**
      * Create a new instance of NoneFunctionChoiceBehavior.
      */
-    public NoneFunctionChoiceBehavior(List<KernelFunction<?>> functions,
-        FunctionChoiceBehaviorOptions options) {
+    public NoneFunctionChoiceBehavior(@Nullable List<KernelFunction<?>> functions,
+                                      @Nullable FunctionChoiceBehaviorOptions options) {
         super(functions, options);
     }
 }

semantickernel-api/src/main/java/com/microsoft/semantickernel/functionchoice/RequiredFunctionChoiceBehavior.java

@@ -3,6 +3,7 @@
 
 import com.microsoft.semantickernel.semanticfunctions.KernelFunction;
 
+import javax.annotation.Nullable;
 import java.util.List;
 
 public class RequiredFunctionChoiceBehavior extends AutoFunctionChoiceBehavior {
@@ -14,8 +15,9 @@ public class RequiredFunctionChoiceBehavior extends AutoFunctionChoiceBehavior {
      * @param functions  A set of functions to advertise to the model.
      * @param options    Options for the function choice behavior.
      */
-    public RequiredFunctionChoiceBehavior(boolean autoInvoke, List<KernelFunction<?>> functions,
-        FunctionChoiceBehaviorOptions options) {
+    public RequiredFunctionChoiceBehavior(boolean autoInvoke,
+                                          @Nullable List<KernelFunction<?>> functions,
+                                          @Nullable FunctionChoiceBehaviorOptions options) {
         super(autoInvoke, functions, options);
     }
 }