return method.getGenericParameterTypes()[0];
  }

  @SuppressWarnings({"rawtypes", "unchecked"})
  private static Type getSupertype(Type type, Class<?> superclass) {
    Class rawType = superclass;
    return TypeToken.of(type).getSupertype(rawType).getType();
  }

  private static Type getSubtype(Type type, Class<?> subclass) {
    return TypeToken.of(type).getSubtype(subclass).getType();
  }