code: private <E extends Event> EventListener<E> getEventListener(E event) {
          @SuppressWarnings("unchecked")
          EventListener<E> eventListener = (EventListener<E>) eventListenerMap.get(event.getClass());
          return eventListener;
      }
docs: Get associated {@link EventListener}
  
  @param event event
  @param <E>   event type
  @return associated {@link EventListener}