Iterators.addAll(result, c.iterator());
    return result;
  }

  // Serialization Support

  private static final long serialVersionUID = 5;

  Object writeReplace() {
    return new SerializationProxy<>(
        entryHelper.keyStrength(),
        entryHelper.valueStrength(),
        keyEquivalence,
        entryHelper.valueStrength().defaultEquivalence(),