code: private void deliverBeatGridUpdate(int player, BeatGrid beatGrid) {
          if (!getBeatGridListeners().isEmpty()) {
              final BeatGridUpdate update = new BeatGridUpdate(player, beatGrid);
              for (final BeatGridListener listener : getBeatGridListeners()) {
                  try {
                      listener.beatGridChanged(update);
  
                  } catch (Throwable t) {
                      logger.warn("Problem delivering beat grid update to listener", t);
                  }
              }
          }
      }
docs: Send a beat grid update announcement to all registered listeners.
  
  @param player the player whose beat grid information has changed
  @param beatGrid the new beat grid associated with that player, if any