Type definition error: [simple type, class cn.hutool.json.JSONNull]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class cn.hutool.json.JSONNull and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: cn.acgo.pms.model.ResponseData["data"]->cn.acgo.pms.service.http.response.TestCaseDownloadVo["testCaseList"]->cn.hutool.json.JSONObject["testCaseInput"])