private Singleton() {}
    }
  }

  static class FactoryMethodParameterNotInstantiable {

    private FactoryMethodParameterNotInstantiable() {}

    static FactoryMethodParameterNotInstantiable create(
        @SuppressWarnings("unused") NotInstantiable x) {
      return new FactoryMethodParameterNotInstantiable();
    }
  }

  static class ConstructorThrows {