code: @Implementation
    protected void adjustStreamVolume(int streamType, int direction, int flags) {
      switch (direction) {
        case AudioManager.ADJUST_MUTE:
          streamsMuteState.put(streamType, true);
          break;
        case AudioManager.ADJUST_UNMUTE:
          streamsMuteState.put(streamType, false);
          break;
        default:
          break;
      }
    }
docs: Implements {@link AudioManager#adjustStreamVolume(int, int, int)}.
  
  <p>Currently supports only the directions {@link AudioManager#ADJUST_MUTE} and {@link
  AudioManager#ADJUST_UNMUTE}.