}

  /**
   * Returns a future that delegates to another but will finish early (via a {@link
   * TimeoutException} wrapped in an {@link ExecutionException}) if the specified duration expires.
   *
   * <p>The delegate future is interrupted and cancelled if it times out.
   *
   * @param delegate The future to delegate to.
   * @param unit the time unit of the time parameter

    // then we know it must have given a pending toString value earlier. If not, then the future
    // completed after the timeout expired, and the message might be success.
    if (isDone()) {
      throw new TimeoutException(message + " but future completed as timeout expired");
    }
    throw new TimeoutException(message + " for " + futureToString);
  }

  /**
   * {@inheritDoc}
   *

   * useful in testing, or to disable caching temporarily without a code change.
   *
   * <p>Expired entries may be counted in {@link Cache#size}, but will never be visible to read or
   * write operations. Expired entries are cleaned up as part of the routine maintenance described
   * in the class javadoc.
   *