refactor: convert Optional<LiveRequestQueue> to @nullable param in Runner

PiperOrigin-RevId: 879517819

Author: tilgalas

core/src/main/java/com/google/adk/runner/Runner.java

@@ -591,9 +591,9 @@ private void copySessionStates(Session source, Session target) {
    * @return invocation context configured for a live run.
    */
   private InvocationContext newInvocationContextForLive(
-      Session session, Optional<LiveRequestQueue> liveRequestQueue, RunConfig runConfig) {
+      Session session, @Nullable LiveRequestQueue liveRequestQueue, RunConfig runConfig) {
     RunConfig.Builder runConfigBuilder = RunConfig.builder(runConfig);
-    if (liveRequestQueue.isPresent()) {
+    if (liveRequestQueue != null) {
       // Default to AUDIO modality if not specified.
       if (CollectionUtils.isNullOrEmpty(runConfig.responseModalities())) {
         runConfigBuilder.setResponseModalities(
@@ -614,8 +614,9 @@ private InvocationContext newInvocationContextForLive(
     InvocationContext.Builder builder =
         newInvocationContextBuilder(session)
             .runConfig(runConfigBuilder.build())
-            .userContent(Content.fromParts());
-    liveRequestQueue.ifPresent(builder::liveRequestQueue);
+            .userContent(Content.fromParts())
+            .liveRequestQueue(liveRequestQueue);
+
     return builder.build();
   }
 
@@ -643,7 +644,7 @@ public Flowable<Event> runLive(
     return Flowable.defer(
             () -> {
               InvocationContext invocationContext =
-                  newInvocationContextForLive(session, Optional.of(liveRequestQueue), runConfig);
+                  newInvocationContextForLive(session, liveRequestQueue, runConfig);
 
               Single<InvocationContext> invocationContextSingle;
               if (invocationContext.agent() instanceof LlmAgent agent) {

core/src/test/java/com/google/adk/runner/InputAudioTranscriptionTest.java

@@ -33,7 +33,6 @@
 import com.google.genai.types.Modality;
 import com.google.genai.types.Part;
 import java.lang.reflect.Method;
-import java.util.Optional;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -50,10 +49,9 @@ private InvocationContext invokeNewInvocationContextForLive(
       throws Exception {
     Method method =
         Runner.class.getDeclaredMethod(
-            "newInvocationContextForLive", Session.class, Optional.class, RunConfig.class);
+            "newInvocationContextForLive", Session.class, LiveRequestQueue.class, RunConfig.class);
     method.setAccessible(true);
-    return (InvocationContext)
-        method.invoke(runner, session, Optional.of(liveRequestQueue), runConfig);
+    return (InvocationContext) method.invoke(runner, session, liveRequestQueue, runConfig);
   }
 
   @Test