}

  static class DurationSpec {
    private final long duration;
    private final TimeUnit unit;

    private DurationSpec(long duration, TimeUnit unit) {
      this.duration = duration;
      this.unit = unit;
    }

    public static DurationSpec of(long duration, TimeUnit unit) {
      return new DurationSpec(duration, unit);
    }

    @Override
    public int hashCode() {

  }

  static class DurationSpec {
    private final long duration;
    private final TimeUnit unit;

    private DurationSpec(long duration, TimeUnit unit) {
      this.duration = duration;
      this.unit = unit;
    }

    public static DurationSpec of(long duration, TimeUnit unit) {
      return new DurationSpec(duration, unit);
    }

    @Override
    public int hashCode() {

 *   <li>{@code maximumWeight=[long]}: sets {@link CacheBuilder#maximumWeight}.
 *   <li>{@code expireAfterAccess=[duration]}: sets {@link CacheBuilder#expireAfterAccess}.
 *   <li>{@code expireAfterWrite=[duration]}: sets {@link CacheBuilder#expireAfterWrite}.
 *   <li>{@code refreshAfterWrite=[duration]}: sets {@link CacheBuilder#refreshAfterWrite}.
 *   <li>{@code weakKeys}: sets {@link CacheBuilder#weakKeys}.

  static long toNanosSaturated(Duration duration) {
    // Using a try/catch seems lazy, but the catch block will rarely get invoked (except for
    // durations longer than approximately +/- 292 years).
    try {
      return duration.toNanos();
    } catch (ArithmeticException tooBig) {
      return duration.isNegative() ? Long.MIN_VALUE : Long.MAX_VALUE;
    }
  }

  private Internal() {}

  static long toNanosSaturated(Duration duration) {
    // Using a try/catch seems lazy, but the catch block will rarely get invoked (except for
    // durations longer than approximately +/- 292 years).
    try {
      return duration.toNanos();
    } catch (ArithmeticException tooBig) {
      return duration.isNegative() ? Long.MIN_VALUE : Long.MAX_VALUE;
    }
  }

  private Internal() {}

  @SuppressWarnings("GoodTime") // duration decomposition
  private static long toNanosSaturated(java.time.Duration duration) {
    // Using a try/catch seems lazy, but the catch block will rarely get invoked (except for
    // durations longer than approximately +/- 292 years).
    try {
      return duration.toNanos();
    } catch (ArithmeticException tooBig) {

  private static Thread acquireFor(final Lock lock, final long duration, final TimeUnit unit) {
    final CountDownLatch latch = new CountDownLatch(1);
    Thread thread =
        new Thread() {
          @Override
          public void run() {
            lock.lock();
            latch.countDown();
            try {
              Thread.sleep(unit.toMillis(duration));
            } catch (InterruptedException e) {

 *   <li>{@code maximumWeight=[long]}: sets {@link CacheBuilder#maximumWeight}.
 *   <li>{@code expireAfterAccess=[duration]}: sets {@link CacheBuilder#expireAfterAccess}.
 *   <li>{@code expireAfterWrite=[duration]}: sets {@link CacheBuilder#expireAfterWrite}.
 *   <li>{@code refreshAfterWrite=[duration]}: sets {@link CacheBuilder#refreshAfterWrite}.
 *   <li>{@code weakKeys}: sets {@link CacheBuilder#weakKeys}.

  private static Thread acquireFor(final Lock lock, final long duration, final TimeUnit unit) {
    final CountDownLatch latch = new CountDownLatch(1);
    Thread thread =
        new Thread() {
          @Override
          public void run() {
            lock.lock();
            latch.countDown();
            try {
              Thread.sleep(unit.toMillis(duration));
            } catch (InterruptedException e) {

  @GwtIncompatible // java.time.Duration
  @SuppressWarnings("Java7ApiChecker") // no more dangerous that wherever the user got the Duration
  @IgnoreJRERequirement
  public static <T extends @Nullable Object> Supplier<T> memoizeWithExpiration(
      Supplier<T> delegate, Duration duration) {
    checkNotNull(delegate);
    // The alternative of `duration.compareTo(Duration.ZERO) > 0` causes J2ObjC trouble.
    checkArgument(