this.bus = checkNotNull(bus);
  }

  /** Registers all subscriber methods on the given listener object. */
  void register(Object listener) {
    Multimap<Class<?>, Subscriber> listenerMethods = findAllSubscribers(listener);

    for (Entry<Class<?>, Collection<Subscriber>> entry : listenerMethods.asMap().entrySet()) {
      Class<?> eventType = entry.getKey();
      Collection<Subscriber> eventMethodsInListener = entry.getValue();