* already have to deal with, thanks to DI frameworks that perform field and method injection,
     * frameworks like Android that define post-construct hooks like Activity.onCreate, etc.
     */

    @CheckForNull private ValueSetLink<K, V> predecessorInValueSet;
    @CheckForNull private ValueSetLink<K, V> successorInValueSet;

  }

  public void testToString() {
    // With ports.
    assertEquals("foo:101", "" + HostAndPort.fromString("foo:101"));
    assertEquals(":102", HostAndPort.fromString(":102").toString());
    assertEquals("[1::2]:103", HostAndPort.fromParts("1::2", 103).toString());
    assertEquals("[::1]:104", HostAndPort.fromString("[::1]:104").toString());

    // Without ports.
    assertEquals("foo", "" + HostAndPort.fromString("foo"));

    bus.register(recorder);

    bus.post(FIRST);

    assertEquals(
        "EventRecorder expected events in order",
        Lists.<Object>newArrayList(FIRST, SECOND),
        recorder.eventsReceived);
  }

  public class EventProcessor {
    @Subscribe
    public void listenForStrings(String event) {
      bus.post(SECOND);
    }
  }

  public class EventRecorder {

    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());

  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.
  }

 * could in principle cause problems for some users. Still, we expect that the benefits of the
 * nullness annotations in particular will outweigh the costs. (And it's worth noting that we have
 * released multiple ListenableFuture.class files that are not byte-for-byte compatible even from
 * the beginning, thanks to using different `-source -target` values for compiling our `-jre` and

 * `Function<@Nullable A, @Nullable B>` already had to find a workaround. Still, there is a *ton* of
 * fallout from trying to switch. I would be shocked if the switch would offer benefits to anywhere
 * near enough users to justify the costs.
 *
 * Fortunately, if anyone does want to use a Converter as a `Function<@Nullable A, @Nullable B>`,
 * it's easy to get one: `converter::convert`.
 *
 * [*] In annotating this class, we're ignoring LegacyConverter.

    }

    /**
     * Performs routine cleanup prior to executing a write. This should be called every time a write
     * thread acquires the segment lock, immediately after acquiring the lock.
     *
     * <p>Post-condition: expireEntries has been run.
     */
    @GuardedBy("this")
    void preWriteCleanup(long now) {
      runLockedCleanup(now);
    }

    /** Performs routine cleanup following a write. */

  }

  public void testToString() {
    // With ports.
    assertEquals("foo:101", "" + HostAndPort.fromString("foo:101"));
    assertEquals(":102", HostAndPort.fromString(":102").toString());
    assertEquals("[1::2]:103", HostAndPort.fromParts("1::2", 103).toString());
    assertEquals("[::1]:104", HostAndPort.fromString("[::1]:104").toString());

    // Without ports.
    assertEquals("foo", "" + HostAndPort.fromString("foo"));

      }
    };
  }

  /**
   * Returns an unmodifiable {@code Iterable} over the nodes reachable from {@code startNode}, in
   * the order of a depth-first post-order traversal. "Post-order" implies that nodes appear in the
   * {@code Iterable} in the order in which they are visited for the last time.
   *