labelQueue.add(label);
    }

    /**
     * Dispatches all listeners {@linkplain #enqueue enqueued} prior to this call, serially and in
     * order.
     */
    @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
    void dispatch() {
      boolean scheduleEventRunner = false;
      synchronized (this) {
        if (!isThreadScheduled) {
          isThreadScheduled = true;

  @ParametricNullness private final V value;

  ImmediateFuture(@ParametricNullness V value) {
    this.value = value;
  }

  @Override
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  public void addListener(Runnable listener, Executor executor) {
    checkNotNull(listener, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");
    try {

      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
    return callWithTimeout(callable, timeoutDuration, timeoutUnit);
  }

  @Override
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  public void runWithTimeout(Runnable runnable, long timeoutDuration, TimeUnit timeoutUnit) {
    checkNotNull(runnable);
    checkNotNull(timeoutUnit);
    try {
      runnable.run();

   *     remove()}, {@code set()}, and {@code add()} calls
   */
  protected void verify(List<E> elements) {}

  /** Executes the test. */
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  public final void test() {
    try {
      recurse(0);
    } catch (Exception e) { // sneaky checked exception
      throw new RuntimeException(Arrays.toString(stimuli), e);

    if (this instanceof ScheduledFuture) {
      return "remaining delay=[" + ((ScheduledFuture) this).getDelay(MILLISECONDS) + " ms]";
    }
    return null;
  }

  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  private void addPendingString(StringBuilder builder) {
    // Capture current builder length so it can be truncated if this future ends up completing while

    private final Adder adder;

    FailsToPropagateException(Adder adder) {
      this.adder = adder;
    }

    @Override
    @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
    public int add(int a, int b) {
      try {
        return adder.add(a, b);
      } catch (Exception e) { // sneaky checked exception
        // swallow!
        return 0;

     * will still be present. If the composed Executor is an ExecutorService, it can respond to
     * shutdown() by returning tasks queued on that Thread after {@link #worker} drains the queue.
     */
    @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
    private void workOnQueue() {
      boolean interruptedDuringTask = false;
      boolean hasSetRunning = false;
      try {
        while (true) {

    private final Adder adder;

    FailsToPropagateException(Adder adder) {
      this.adder = adder;
    }

    @Override
    @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
    public int add(int a, int b) {
      try {
        return adder.add(a, b);
      } catch (Exception e) { // sneaky checked exception
        // swallow!
        return 0;

  }

  /**
   * Submits the given runnable to the given {@link Executor} catching and logging all {@linkplain
   * RuntimeException runtime exceptions} thrown by the executor.
   */
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  private static void executeListener(Runnable runnable, Executor executor) {
    try {
      executor.execute(runnable);
    } catch (Exception e) { // sneaky checked exception

   *     remove()}, {@code set()}, and {@code add()} calls
   */
  protected void verify(List<E> elements) {}

  /** Executes the test. */
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  public final void test() {
    try {
      recurse(0);
    } catch (Exception e) { // sneaky checked exception
      throw new RuntimeException(Arrays.toString(stimuli), e);