@Override
          public LoadingCache<Key, String> apply(CacheBuilder<Object, Object> builder) {
            return builder.build(KEY_TO_STRING_LOADER);
          }
        });
  }

  public void testContainsKeyAndValue() {
    for (LoadingCache<Key, String> cache : caches()) {
      // maintain strong refs so these won't be collected, regardless of cache's key/value strength
      Key key = new Key(1);