tester.testAllPublicInstanceMethods(new MapMaker());
  }

  @GwtIncompatible // threads
  static final class DelayingIdentityLoader<T> implements Function<T, T> {
    private final CountDownLatch delayLatch;

    DelayingIdentityLoader(CountDownLatch delayLatch) {
      this.delayLatch = delayLatch;
    }

    @CanIgnoreReturnValue // Sure, why not?
    @Override