@Subscribe
    public void handle(Integer i) {}
  }

  public static class ObjectSubscriber {

    @Subscribe
    public void handle(Object o) {}
  }

  public void testFlattenHierarchy() {
    assertEquals(
        ImmutableSet.of(
            Object.class,
            HierarchyFixtureInterface.class,
            HierarchyFixtureSubinterface.class,
            HierarchyFixtureParent.class,