*
   * @param event event to post.
   */
  public void post(Object event) {
    Iterator<Subscriber> eventSubscribers = subscribers.getSubscribers(event);
    if (eventSubscribers.hasNext()) {
      dispatcher.dispatch(event, eventSubscribers);
    } else if (!(event instanceof DeadEvent)) {
      // the event had no subscribers and was not itself a DeadEvent
      post(new DeadEvent(this, event));
    }
  }

    return subscriber;
  }

  @Override
  protected void setUp() throws Exception {
    subscriber = createSubscriber();
    EventBus bus = new EventBus();
    bus.register(subscriber);
    bus.post(EVENT);
  }

  @Override
  protected void tearDown() throws Exception {
    subscriber = null;
  }

          @Subscribe
          public void accept(String str) {
            holder.set(str);
            deliveries.incrementAndGet();
          }
        });

    String EVENT = "Hello!";
    bus.post(EVENT);

    assertEquals("Only one event should be delivered.", 1, deliveries.get());
    assertEquals("Correct string should be delivered.", EVENT, holder.get());
  }

    bus = new AsyncEventBus(executor);
  }

  public void testBasicDistribution() {
    StringCatcher catcher = new StringCatcher();
    bus.register(catcher);

    // We post the event, but our Executor will not deliver it until instructed.
    bus.post(EVENT);

    List<String> events = catcher.getEvents();
    assertTrue("No events should be delivered synchronously.", events.isEmpty());

  @GwtIncompatible // SerializableTester
  public void testIsNull_serialization() {
    Predicate<String> pre = Predicates.isNull();
    Predicate<String> post = SerializableTester.reserializeAndAssert(pre);
    assertEquals(pre.apply("foo"), post.apply("foo"));
    assertEquals(pre.apply(null), post.apply(null));
  }

  public void testNotNull_apply() {
    Predicate<@Nullable Integer> notNull = Predicates.notNull();

      };

  enum Traversal {
    PRE_ORDER {
      @Override
      <T> Iterable<T> view(T root, TreeTraverser<T> viewer) {
        return viewer.preOrderTraversal(root);
      }
    },
    POST_ORDER {
      @Override
      <T> Iterable<T> view(T root, TreeTraverser<T> viewer) {
        return viewer.postOrderTraversal(root);
      }
    },
    BREADTH_FIRST {
      @Override

  void setUp() {
    eventBus = new EventBus("for benchmarking purposes");
    eventBus.register(this);
  }

  @Benchmark
  void postStrings(int reps) {
    for (int i = 0; i < reps; i++) {
      eventBus.post("hello there");
    }
  }

  @Subscribe
  public void handleStrings(String string) {
    // Nothing to do here.
  }

    return subscriber;
  }

  @Override
  protected void setUp() throws Exception {
    subscriber = createSubscriber();
    EventBus bus = new EventBus();
    bus.register(subscriber);
    bus.post(EVENT);
  }

  @Override
  protected void tearDown() throws Exception {
    subscriber = null;
  }

      if (childItr.hasNext()) {
        stack.addLast(childItr);
      }
      return result;
    }
  }

  /**
   * Returns an unmodifiable iterable over the nodes in a tree structure, using post-order
   * traversal. That is, each node's subtrees are traversed before the node itself is returned.
   *
   * <p>No guarantees are made about the behavior of the traversal when nodes change while iteration

      </plugin>
      <plugin>
        <artifactId>maven-source-plugin</artifactId>
        <executions>
          <execution>
            <id>attach-test-sources</id>
            <phase>post-integration-test</phase>
            <goals><goal>test-jar</goal></goals>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <artifactId>maven-jar-plugin</artifactId>