Add custom media notifcation actions

Question

I started building a Material 3 Expressive music player app built mainly on Java (~85%).

To prevent confusion, I'll provide a direct link to the entire thing just in case: Main Player Service | CustomNotificationProvider

My main setup parts:

@Override 
public void onCreate() { 
 super.onCreate(); 
 fallbackUri = Uri.parse("android.resource://" + this.getPackageName() + "/" + resId);
 handlerThread.start();
 Looper backgroundLooper = handlerThread.getLooper();
 ExoPlayerHandler = new Handler(backgroundLooper);
 DefaultRenderersFactory renderersFactory = new DefaultRenderersFactory(this).setExtensionRendererMode(DefaultRenderersFactory.EXTENSION_RENDERER_MODE_ON);
 player = new ExoPlayer.Builder(this, renderersFactory).setLooper(backgroundLooper).build();
 androidx.media3.common.AudioAttributes attrs = new androidx.media3.common.AudioAttributes.Builder()
 .setUsage(C.USAGE_MEDIA)
 .setContentType(C.AUDIO_CONTENT_TYPE_MUSIC)
 .build();
 ExoPlayerHandler.post(() -> {
 player.setAudioAttributes(attrs, true);
 });
 handler = new Handler(Looper.getMainLooper()); 
 if (!isBuilt) {
 setupMediaSession();
 isBuilt = true;
 }
 isNotifDead = false;
 createNotificationChannel(); 
 audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
 setupAudioFocusRequest();
 setMediaNotificationProvider(new CustomNotificationProvider(this));
 if (Build.VERSION.SDK_INT >= 33) { 
 startForeground(NOTIFICATION_ID, buildNotification("XMusic", "No song is playing", "") , ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PLAYBACK); 
 } else { 
 startForeground(NOTIFICATION_ID, buildNotification("XMusic", "No song is playing", "")); 
 } 
}

private Notification buildNotification(String title, String artist, String cover) {
 if (mediaSession == null) {
 setupMediaSession();
 }
 MediaStyleNotificationHelper.MediaStyle mediaStyle = new MediaStyleNotificationHelper.MediaStyle(mediaSession).setShowCancelButton(true);
 Intent resumeIntent = c.getPackageManager().getLaunchIntentForPackage(c.getPackageName());
 PendingIntent contentIntent = PendingIntent.getActivity(c, 0, resumeIntent, PendingIntent.FLAG_IMMUTABLE);
 return new NotificationCompat.Builder(this, CHANNEL_ID)
 .setSmallIcon(R.mipmap.ic_launcher_foreground)
 .setContentTitle(title)
 .setContentText(artist)
 .setLargeIcon(current)
 .setStyle(mediaStyle)
 .setOngoing(true)
 .setContentIntent(contentIntent)
 .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
 .build();
}

private void setupMediaSession() {
 if (mediaSession != null) {
 return;
 }
 mediaSession = new androidx.media3.session.MediaSession.Builder(this, player).setId("XMusicMediaSessionPrivate").setCallback(new CustomCallback()).build();
}
public class CustomCallback implements MediaSession.Callback {
 
 final SessionCommand TEST = new SessionCommand("TEST_ACTION", Bundle.EMPTY);
 final CommandButton TEST_BUTTON = new CommandButton.Builder(R.drawable.ic_shuffle).setDisplayName("shuffle").setSessionCommand(TEST).setSlots(CommandButton.SLOT_FORWARD_SECONDARY).build();
 List<CommandButton> list = ImmutableList.of(TEST_BUTTON);
 Player.Commands pcs = new Player.Commands.Builder().addAllCommands().add(Player.COMMAND_SET_SHUFFLE_MODE).build();
 private SessionCommands sc = SessionCommands.EMPTY.buildUpon().add(TEST).build();
 @Override
 public ConnectionResult onConnect(MediaSession mediaSession, ControllerInfo controllerInfo) {
 //return new ConnectionResult.AcceptedResultBuilder(mediaSession).setCustomLayout(list).setAvailableSessionCommands(sc).setMediaButtonPreferences(ImmutableList.of(TEST_BUTTON)).build();
 return ConnectionResult.accept(sc, pcs);
 }
 
 @Override
 public void onPostConnect(MediaSession mediaSession, ControllerInfo controllerInfo) {
 mediaSession.setAvailableCommands(controllerInfo, sc, pcs);
 mediaSession.setCustomLayout(controllerInfo, list);
 }
 
 @Override
 public ListenableFuture<SessionResult> onCustomCommand(MediaSession mediaSession, ControllerInfo controllerInfo, SessionCommand sessionCommand, Bundle bundle) {
 return Futures.immediateFuture(new SessionResult(-6));
 }
}

public class CustomNotificationProvider extends DefaultMediaNotificationProvider {
 private Context c;
 public CustomNotificationProvider(Context context) {
 super(context);
 c = context;
 }
 
 @Override
 public int[] addNotificationActions(MediaSession mediaSession, ImmutableList<CommandButton> mediaButtons, NotificationCompat.Builder builder, MediaNotification.ActionFactory actionFactory) {
 CommandButton cb = new CommandButton.Builder(R.drawable.ic_shuffle).setDisplayName("negro").setSessionCommand(new SessionCommand("action_nigga", Bundle.EMPTY)).setSlots(CommandButton.SLOT_BACK_SECONDARY).build();
 ImmutableList<CommandButton> l = ImmutableList.of(cb);
 NotificationCompat.Action action = actionFactory.createCustomAction(mediaSession, IconCompat.createWithResource(c, R.drawable.ic_shuffle), "test", "test", Bundle.EMPTY);
 builder.addAction(action);
 int[] i = super.addNotificationActions(mediaSession, l, builder, actionFactory);
 return i;
 } 
 
 @Override
 public ImmutableList<CommandButton> getMediaButtons(MediaSession mediaSession, Player.Commands commands, ImmutableList<CommandButton> mediaButtonPreferences, boolean z) {
 CommandButton cb = new CommandButton.Builder(R.drawable.ic_shuffle).setDisplayName("negro").setSessionCommand(new SessionCommand("action_nigga", Bundle.EMPTY)).setSlots(CommandButton.SLOT_BACK_SECONDARY).build();
 ImmutableList<CommandButton> l = ImmutableList.of(cb);
 return l;
 }
 private PendingIntent getSessionActivityPendingIntent(MediaSession session) {
 return session.getSessionActivity();
 }
}

I've been trying to add custom notification actions to my media notification, but no matter what I tried, only default notification actions (seek buttons, seek bar and play/pause toggle) keep showing like this: