Criar um Xstream que ignora atributos desconhecidos

public XStream getXStream() {
  XStream xstream = new XStream() {
    @Override
    protected MapperWrapper wrapMapper(MapperWrapper next) {
      return new MapperWrapper(next) {
        @Override
        public boolean shouldSerializeMember(Class definedIn, String fieldName) {
          if (definedIn == Object.class) {
            return false;
          }
          return super.shouldSerializeMember(definedIn, fieldName);
        }
      };
    }
  };
  return xstream;
}