Object writeReplace() {
      return new ManualSerializationProxy<>(localCache);
    }

    private void readObject(ObjectInputStream in) throws InvalidObjectException {
      throw new InvalidObjectException("Use ManualSerializationProxy");
    }
  }

  // TODO(cpovirk): Make this final (but that may break proxies).
  static class LocalLoadingCache<K, V> extends LocalManualCache<K, V>