}

  @GwtIncompatible // concurrency

  public void testConcurrentAdvance() throws Exception {
    final FakeTicker ticker = new FakeTicker();

    int numberOfThreads = 64;
    runConcurrentTest(
        numberOfThreads,
        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker