docs: @Override
      public void registerBroadcastListener(String broadcastName, BroadcastListener broadcastListener) {
          broadcastListeners.putIfAbsent(broadcastName, new ArrayList<BroadcastListener>());
          List<BroadcastListener> listeners = broadcastListeners.get(broadcastName);
          synchronized (listeners) {
              listeners.add(broadcastListener);
          }
      }