}
  }

  /*
   * Notes on EnumSet and <E extends Enum<E>>:
   *
   * This class isn't an arbitrary ForwardingImmutableSet because we need to
   * know that calling {@code clone()} during deserialization will return an
   * object that no one else has a reference to, allowing us to guarantee
   * immutability. Hence, we support only {@link EnumSet}.
   */
  private final transient EnumSet<E> delegate;

    }
  }

  /*
   * Notes on EnumSet and <E extends Enum<E>>:
   *
   * This class isn't an arbitrary ForwardingImmutableSet because we need to
   * know that calling {@code clone()} during deserialization will return an
   * object that no one else has a reference to, allowing us to guarantee
   * immutability. Hence, we support only {@link EnumSet}.
   */
  private final transient EnumSet<E> delegate;