code: public void addMessageListener(Class<? extends Message> messageClass, MessageListener<Message> messageListener) {
          addMessageListener(messageListener.getChannelIdentifier(), messageClass, messageListener);
      }
docs: Add a generic message listener to listen for a specific type of message. Useful if you want to combine
  several or more message handlers into one bucket.
  @param messageClass Message class to listen to from the project board.
  @param messageListener (Generic)Listener that will fire whenever the message type is received.