subscriber(bus, i2, "handleInteger", Integer.class),
          subscriber(bus, i3, "handleInteger", Integer.class));

  private final StringSubscriber s1 = new StringSubscriber("s1");
  private final StringSubscriber s2 = new StringSubscriber("s2");
  private final ImmutableList<Subscriber> stringSubscribers =
      ImmutableList.of(
          subscriber(bus, s1, "handleString", String.class),