MediaController2: Add @Nullable to getConnectedSessionToken()

Bug: 126699575
Test: Build
Change-Id: Ic18166991bd3c4d5f3ed93fdcaf80562b4883435
diff --git a/api/current.txt b/api/current.txt
index 1b1c693..e9c88a2 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -24663,7 +24663,7 @@
     ctor public MediaController2(@NonNull android.content.Context, @NonNull android.media.Session2Token, @NonNull java.util.concurrent.Executor, @NonNull android.media.MediaController2.ControllerCallback);
     method public void cancelSessionCommand(@NonNull Object);
     method public void close();
-    method public android.media.Session2Token getConnectedSessionToken();
+    method @Nullable public android.media.Session2Token getConnectedSessionToken();
     method public boolean isPlaybackActive();
     method @NonNull public Object sendSessionCommand(@NonNull android.media.Session2Command, @Nullable android.os.Bundle);
   }
diff --git a/media/apex/java/android/media/MediaController2.java b/media/apex/java/android/media/MediaController2.java
index 2709df0..2743a34 100644
--- a/media/apex/java/android/media/MediaController2.java
+++ b/media/apex/java/android/media/MediaController2.java
@@ -181,6 +181,7 @@
      *
      * @return Session2Token of the connected session, or {@code null} if not connected
      */
+    @Nullable
     public Session2Token getConnectedSessionToken() {
         synchronized (mLock) {
             return mConnectedToken;