code: @Override
      public void unregisterBroadcastListener(String broadcastName, BroadcastListener broadcastListener) {
          List<BroadcastListener> listeners = broadcastListeners.get(broadcastName);
          if (listeners == null) {
              LOG.error("trying to unregister a listener for broadcast \"" + broadcastName
                      + "\" that was never registered");
              return;
          }
          synchronized (listeners) {
              boolean success = listeners.remove(broadcastListener);
              if (!success) {
                  LOG.error("trying to unregister a listener for broadcast \"" + broadcastName
                          + "\" that was never registered");
                  return;
              }
          }
      }
docs: Unregisters a broadcast listener.
  
  @param broadcastName     the broadcast name as defined in the Franca model
  to unsubscribe from.
  @param broadcastListener the listener to remove.