return (ReferenceEntry<K, V>) NullEntry.INSTANCE;
  }

  static final Queue<?> DISCARDING_QUEUE =
      new AbstractQueue<Object>() {
        @Override
        public boolean offer(Object o) {
          return true;
        }

        @CheckForNull
        @Override
        public Object peek() {
          return null;
        }

        @CheckForNull
        @Override

    return (ReferenceEntry<K, V>) NullEntry.INSTANCE;
  }

  static final Queue<?> DISCARDING_QUEUE =
      new AbstractQueue<Object>() {
        @Override
        public boolean offer(Object o) {
          return true;
        }

        @CheckForNull
        @Override
        public Object peek() {
          return null;
        }

        @CheckForNull
        @Override