@GwtIncompatible // ScheduledExecutorService
  @IgnoreJRERequirement // Users will use this only if they're already using Duration.
  public final FluentFuture<V> withTimeout(
      Duration timeout, ScheduledExecutorService scheduledExecutor) {
    return withTimeout(toNanosSaturated(timeout), TimeUnit.NANOSECONDS, scheduledExecutor);
  }

  /**
   * Returns a future that delegates to this future but will finish early (via a {@link

 *       thread, an RPC, etc. The {@code Future} is also "completed" if it fails "early" -- for
 *       example, if the deadline expires on a {@code Future} returned from {@link
 *       Futures#withTimeout} while the {@code Future} it wraps continues its underlying work. So
 *       beware: <i>Your {@code AsyncCallable} should not complete its {@code Future} until it is
 *       safe for the next task to start.</i>
 * </ul>
 *