* state: BLOCKED, WAITING, or TIMED_WAITING.
   */
  void waitForThreadToEnterWaitState(Thread thread, long timeoutMillis) {
    long startTime = System.nanoTime();
    for (; ; ) {
      Thread.State s = thread.getState();
      if (s == Thread.State.BLOCKED || s == Thread.State.WAITING || s == Thread.State.TIMED_WAITING)
        return;

    this.range = GeneralRange.all(comparator);
    this.header = new AvlNode<>();
    successor(header, header);
    this.rootReference = new Reference<>();
  }

  /** A function which can be summed across a subtree. */
  private enum Aggregate {
    SIZE {
      @Override
      int nodeAggregate(AvlNode<?> node) {
        return node.elemCount;
      }

      @Override

   * Elements are added in encounter order.
   *
   * <p>If the mapped elements contain duplicates (according to {@link Object#equals}), the element
   * will be added more than once, with the count summed over all appearances of the element.
   *
   * <p>Note that {@code stream.collect(toMultiset(function, e -> 1, supplier))} is equivalent to
   * {@code stream.map(function).collect(Collectors.toCollection(supplier))}.
   *

  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033
  public static void awaitDone(Future<?> future) {
    if (future.isDone()) {
      return;
    }

   * state: BLOCKED, WAITING, or TIMED_WAITING.
   */
  void waitForThreadToEnterWaitState(Thread thread, long timeoutMillis) {
    long startTime = System.nanoTime();
    for (; ; ) {
      Thread.State s = thread.getState();
      if (s == Thread.State.BLOCKED || s == Thread.State.WAITING || s == Thread.State.TIMED_WAITING)
        return;

  // Gets and Timed Gets
  //
  // * Be responsive to interruption
  // * Don't create Waiter nodes if you aren't going to park, this helps reduce contention on the
  //   waiters field.
  // * Future completion is defined by when #value becomes non-null/non SetFuture
  // * Future completion can be observed if the waiters field contains a TOMBSTONE

  // Timed Get

              ListenableFuture<String> a, ListenableFuture<String> b) {
            return successfulAsList(ImmutableSet.of(a, b));
          }
        };
  }

  /**
   * Very rough equivalent of a timed get, produced by calling the no-arg get method in another
   * thread and waiting a short time for it.
   *
   * <p>We need this to test the behavior of no-arg get methods without hanging the main test thread

  @GwtIncompatible
  @ParametricNullness
  static <T extends @Nullable Object> T invokeAnyImpl(
      ListeningExecutorService executorService,
      Collection<? extends Callable<T>> tasks,
      boolean timed,
      long timeout,
      TimeUnit unit)
      throws InterruptedException, ExecutionException, TimeoutException {
    checkNotNull(executorService);
    checkNotNull(unit);
    int ntasks = tasks.size();

              ListenableFuture<String> a, ListenableFuture<String> b) {
            return successfulAsList(ImmutableSet.of(a, b));
          }
        };
  }

  /**
   * Very rough equivalent of a timed get, produced by calling the no-arg get method in another
   * thread and waiting a short time for it.
   *
   * <p>We need this to test the behavior of no-arg get methods without hanging the main test thread

  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033
  public static void awaitDone(Future<?> future) {
    if (future.isDone()) {
      return;
    }