* uncommon to specify {@code concurrencyLevel(1)} in order to achieve more deterministic eviction
   * behavior.
   *
   * <p>Note that future implementations may abandon segment locking in favor of more advanced
   * concurrency controls.
   *
   * @return this {@code CacheBuilder} instance (for chaining)
   * @throws IllegalArgumentException if {@code concurrencyLevel} is nonpositive

    /*
     * TODO(cpovirk): move ForwardingTestCase somewhere common, and use it to
     * test the forwarded methods
     */
  }

  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
  public void testListeningDecorator_noWrapExecuteTask() {
    ExecutorService delegate = mock(ExecutorService.class);

    MemoizingSupplier(Supplier<T> delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override
    @ParametricNullness
    public T get() {
      // A 2-field variant of Double Checked Locking.
      if (!initialized) {
        synchronized (this) {
          if (!initialized) {
            T t = delegate.get();
            value = t;
            initialized = true;
            return t;

  }

  /**
   * Saves the state to a stream (that is, serializes it). This merely wraps default serialization
   * within the monitor. The serialization strategy for items is left to underlying Queue. Note that
   * locking is not needed on deserialization, so readObject is not defined, just relying on
   * default.
   */
  private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
    monitor.enter();
    try {