code: @JSONField(serialize = false)
      public List<Obj> getRequired() {
          List<Obj> requred = new ArrayList<>();
          if (getList() != null) {
              for (Obj obj : getList()) {
                  if (obj.isRequired()) {
                      requred.add(obj);
                  }
              }
          }
          return requred;
      }
docs: required参数视图，如果不存在毕传参数，那么返回空数组，而不是返回null