code: public synchronized void clearPlaybackState(int player) {
          long oldMaxPosition = 0;
          PlaybackState furthestState = getFurthestPlaybackState();
          if (furthestState != null) {
              oldMaxPosition = furthestState.position;
          }
          PlaybackState oldState = playbackStateMap.remove(player);
          long newMaxPosition = 0;
          furthestState = getFurthestPlaybackState();
          if (furthestState != null) {
              newMaxPosition = furthestState.position;
          }
          repaintDueToPlaybackStateChange(oldMaxPosition, newMaxPosition, oldState, null);
      }
docs: Clear the playback state stored for a player, such as when it has unloaded the track.
  
  @param player the player number whose playback state is no longer valid
  @since 0.5.0