code: protected <L extends Listener, E extends Event<?, ?>> void checkDispatchArgs(
              E event, Object bc, ExceptionCallback ec) {
          if (event == null) {
              throw new IllegalArgumentException("event is null");
          } else if (bc == null) {
              throw new IllegalArgumentException("bc is null");
          } else if (ec == null) {
              throw new IllegalArgumentException("ec is null");
          }
      }
docs: Helper method which serves for throwing {@link IllegalArgumentException}
  if any of the passed arguments is null.
  
  @param <L> Type of the listeners which will be notified.
  @param <E> Type of the event which will be passed to a listener.
  @param event The event.
  @param bc The method to call on the listener
  @param ec The ExceptionCallback
  @throws IllegalArgumentException If any argument is <code>null</code>.