Add Nullable to message payload.

Not having this annotation may cause Kotlin implementations to fail.

Issue:#4802

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=212980643

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/LibvpxVideoRenderer.java

@@ -640,7 +640,7 @@ public class LibvpxVideoRenderer extends BaseRenderer {
   // PlayerMessage.Target implementation.
 
   @Override
-  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public void handleMessage(int messageType, @Nullable Object message) throws ExoPlaybackException {
     if (messageType == C.MSG_SET_SURFACE) {
       setOutput((Surface) message, null);
     } else if (messageType == MSG_SET_OUTPUT_BUFFER_RENDERER) {

library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java

@@ -163,7 +163,7 @@ public abstract class BaseRenderer implements Renderer, RendererCapabilities {
   // PlayerMessage.Target implementation.
 
   @Override
-  public void handleMessage(int what, Object object) throws ExoPlaybackException {
+  public void handleMessage(int what, @Nullable Object object) throws ExoPlaybackException {
     // Do nothing.
   }
 

library/core/src/main/java/com/google/android/exoplayer2/NoSampleRenderer.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2;
 
+import android.support.annotation.Nullable;
 import com.google.android.exoplayer2.source.SampleStream;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.MediaClock;
@@ -182,7 +183,7 @@ public abstract class NoSampleRenderer implements Renderer, RendererCapabilities
   // PlayerMessage.Target implementation.
 
   @Override
-  public void handleMessage(int what, Object object) throws ExoPlaybackException {
+  public void handleMessage(int what, @Nullable Object object) throws ExoPlaybackException {
     // Do nothing.
   }
 

library/core/src/main/java/com/google/android/exoplayer2/PlayerMessage.java

@@ -36,7 +36,7 @@ public final class PlayerMessage {
      * @throws ExoPlaybackException If an error occurred whilst handling the message. Should only be
      *     thrown by targets that handle messages on the playback thread.
      */
-    void handleMessage(int messageType, Object payload) throws ExoPlaybackException;
+    void handleMessage(int messageType, @Nullable Object payload) throws ExoPlaybackException;
   }
 
   /** A sender for messages. */
@@ -55,7 +55,7 @@ public final class PlayerMessage {
   private final Timeline timeline;
 
   private int type;
-  private Object payload;
+  private @Nullable Object payload;
   private Handler handler;
   private int windowIndex;
   private long positionMs;
@@ -134,7 +134,7 @@ public final class PlayerMessage {
   }
 
   /** Returns the message payload forwarded to {@link Target#handleMessage(int, Object)}. */
-  public Object getPayload() {
+  public @Nullable Object getPayload() {
     return payload;
   }
 

library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java

@@ -645,7 +645,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
   }
 
   @Override
-  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public void handleMessage(int messageType, @Nullable Object message) throws ExoPlaybackException {
     switch (messageType) {
       case C.MSG_SET_VOLUME:
         audioSink.setVolume((Float) message);

library/core/src/main/java/com/google/android/exoplayer2/audio/SimpleDecoderAudioRenderer.java

@@ -584,7 +584,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
   }
 
   @Override
-  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public void handleMessage(int messageType, @Nullable Object message) throws ExoPlaybackException {
     switch (messageType) {
       case C.MSG_SET_VOLUME:
         audioSink.setVolume((Float) message);

library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java

@@ -543,7 +543,8 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
 
   @Override
   @SuppressWarnings("unchecked")
-  public final void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public final void handleMessage(int messageType, @Nullable Object message)
+      throws ExoPlaybackException {
     if (player == null) {
       // Stale event.
       return;
@@ -551,13 +552,13 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
     switch (messageType) {
       case MSG_ADD:
         MessageData<Collection<MediaSourceHolder>> addMessage =
-            (MessageData<Collection<MediaSourceHolder>>) message;
+            (MessageData<Collection<MediaSourceHolder>>) Util.castNonNull(message);
         shuffleOrder = shuffleOrder.cloneAndInsert(addMessage.index, addMessage.customData.size());
         addMediaSourcesInternal(addMessage.index, addMessage.customData);
         scheduleListenerNotification(addMessage.actionOnCompletion);
         break;
       case MSG_REMOVE:
-        MessageData<Integer> removeMessage = (MessageData<Integer>) message;
+        MessageData<Integer> removeMessage = (MessageData<Integer>) Util.castNonNull(message);
         int fromIndex = removeMessage.index;
         int toIndex = removeMessage.customData;
         if (fromIndex == 0 && toIndex == shuffleOrder.getLength()) {
@@ -573,14 +574,15 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
         scheduleListenerNotification(removeMessage.actionOnCompletion);
         break;
       case MSG_MOVE:
-        MessageData<Integer> moveMessage = (MessageData<Integer>) message;
+        MessageData<Integer> moveMessage = (MessageData<Integer>) Util.castNonNull(message);
         shuffleOrder = shuffleOrder.cloneAndRemove(moveMessage.index);
         shuffleOrder = shuffleOrder.cloneAndInsert(moveMessage.customData, 1);
         moveMediaSourceInternal(moveMessage.index, moveMessage.customData);
         scheduleListenerNotification(moveMessage.actionOnCompletion);
         break;
       case MSG_SET_SHUFFLE_ORDER:
-        MessageData<ShuffleOrder> shuffleOrderMessage = (MessageData<ShuffleOrder>) message;
+        MessageData<ShuffleOrder> shuffleOrderMessage =
+            (MessageData<ShuffleOrder>) Util.castNonNull(message);
         shuffleOrder = shuffleOrderMessage.customData;
         scheduleListenerNotification(shuffleOrderMessage.actionOnCompletion);
         break;
@@ -588,7 +590,7 @@ public class ConcatenatingMediaSource extends CompositeMediaSource<MediaSourceHo
         notifyListener();
         break;
       case MSG_ON_COMPLETION:
-        List<Runnable> actionsOnCompletion = ((List<Runnable>) message);
+        List<Runnable> actionsOnCompletion = (List<Runnable>) Util.castNonNull(message);
         Handler handler = Assertions.checkNotNull(playerApplicationHandler);
         for (int i = 0; i < actionsOnCompletion.size(); i++) {
           handler.post(actionsOnCompletion.get(i));

library/core/src/main/java/com/google/android/exoplayer2/video/MediaCodecVideoRenderer.java

@@ -378,7 +378,7 @@ public class MediaCodecVideoRenderer extends MediaCodecRenderer {
   }
 
   @Override
-  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public void handleMessage(int messageType, @Nullable Object message) throws ExoPlaybackException {
     if (messageType == C.MSG_SET_SURFACE) {
       setSurface((Surface) message);
     } else if (messageType == C.MSG_SET_SCALING_MODE) {

library/core/src/main/java/com/google/android/exoplayer2/video/spherical/CameraMotionRenderer.java

@@ -57,7 +57,7 @@ public class CameraMotionRenderer extends BaseRenderer {
   }
 
   @Override
-  public void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+  public void handleMessage(int messageType, @Nullable Object message) throws ExoPlaybackException {
     if (messageType == C.MSG_SET_CAMERA_MOTION_LISTENER) {
       listener = (CameraMotionListener) message;
     } else {

library/core/src/test/java/com/google/android/exoplayer2/ExoPlayerTest.java

@@ -1964,7 +1964,7 @@ public final class ExoPlayerTest {
     Renderer videoRenderer =
         new FakeRenderer(Builder.VIDEO_FORMAT) {
           @Override
-          public void handleMessage(int what, Object object) throws ExoPlaybackException {
+          public void handleMessage(int what, @Nullable Object object) throws ExoPlaybackException {
             super.handleMessage(what, object);
             rendererMessages.add(what);
           }
@@ -2455,7 +2455,7 @@ public final class ExoPlayerTest {
     }
 
     @Override
-    public void handleMessage(SimpleExoPlayer player, int messageType, Object message) {
+    public void handleMessage(SimpleExoPlayer player, int messageType, @Nullable Object message) {
       if (player != null) {
         windowIndex = player.getCurrentWindowIndex();
         positionMs = player.getCurrentPosition();

testutils/src/main/java/com/google/android/exoplayer2/testutil/ActionSchedule.java

@@ -447,7 +447,8 @@ public final class ActionSchedule {
     private SimpleExoPlayer player;
 
     /** Handles the message send to the component and additionally provides access to the player. */
-    public abstract void handleMessage(SimpleExoPlayer player, int messageType, Object message);
+    public abstract void handleMessage(
+        SimpleExoPlayer player, int messageType, @Nullable Object message);
 
     /** Sets the player to be passed to {@link #handleMessage(SimpleExoPlayer, int, Object)}. */
     /* package */ void setPlayer(SimpleExoPlayer player) {
@@ -455,7 +456,8 @@ public final class ActionSchedule {
     }
 
     @Override
-    public final void handleMessage(int messageType, Object message) throws ExoPlaybackException {
+    public final void handleMessage(int messageType, @Nullable Object message)
+        throws ExoPlaybackException {
       handleMessage(player, messageType, message);
     }
   }