return ImmutableSet.of().iterator();
        }
      };

  /** Queue that discards all elements. */
  @SuppressWarnings("unchecked") // impl never uses a parameter or returns any non-null value
  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!

          return ImmutableSet.of().iterator();
        }
      };

  /** Queue that discards all elements. */
  @SuppressWarnings("unchecked") // impl never uses a parameter or returns any non-null value
  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!