*   https://github.com/google/guava/issues/6565
   */
  @SuppressWarnings("AnonymousToLambda")
  static final Supplier<StatsCounter> CACHE_STATS_COUNTER =
      new Supplier<StatsCounter>() {
        @Override
        public StatsCounter get() {
          return new SimpleStatsCounter();
        }
      };

  enum NullListener implements RemovalListener<Object, Object> {
    INSTANCE;