static <E> Queue<E> discardingQueue() {
    return (Queue) DISCARDING_QUEUE;
  }

  /*
   * Note: All of this duplicate code sucks, but it saves a lot of memory. If only Java had mixins!
   * To maintain this code, make a change for the strong reference type. Then, cut and paste, and
   * replace "Strong" with "Soft" or "Weak" within the pasted text. The primary difference is that

    bulkFuture.addListener(
        new Runnable() {
          @Override
          public void run() {
            /*
             * firstFuture just completed, but AggregateFuture hasn't yet had time to record the
             * exception in seenExceptions. When we complete secondFuture with the same exception,
             * we want for AggregateFuture to still detect that it's been previously seen.
             */

    bulkFuture.addListener(
        new Runnable() {
          @Override
          public void run() {
            /*
             * firstFuture just completed, but AggregateFuture hasn't yet had time to record the
             * exception in seenExceptions. When we complete secondFuture with the same exception,
             * we want for AggregateFuture to still detect that it's been previously seen.
             */

  static <E> Queue<E> discardingQueue() {
    return (Queue) DISCARDING_QUEUE;
  }

  /*
   * Note: All of this duplicate code sucks, but it saves a lot of memory. If only Java had mixins!
   * To maintain this code, make a change for the strong reference type. Then, cut and paste, and
   * replace "Strong" with "Soft" or "Weak" within the pasted text. The primary difference is that

        return whenClosed = new CountDownLatch(1);
      }
    }
  }

  /**
   * Returns an object that can be used to wait until this objects' deferred closeables have all had
   * {@link Runnable}s that close them submitted to each one's closing {@link Executor}.
   */
  @VisibleForTesting
  CountDownLatch whenClosedCountDown() {
    return closeables.whenClosedCountDown();
  }