#vulnerable code 
                                @Override
    public void soService(ServiceDataFlowEvent event) {


        DataFlowContext dataFlowContext = event.getDataFlowContext();
        AppService service = event.getAppService();
        JSONObject data = dataFlowContext.getReqJson();

        Assert.hasKeyAndValue(data,"page","请求报文中未包含page节点");
        Assert.hasKeyAndValue(data,"rows","请求报文中未包含rows节点");
        Assert.hasKeyAndValue(data,"storeId","请求报文中未包含storeId节点");
        Assert.hasKeyAndValue(data,"name","请求报文中未包含name节点");
        ResponseEntity<String> responseEntity = null;
        //根据名称查询用户信息
        responseEntity = super.callService(dataFlowContext,ServiceCodeConstant.SERVICE_CODE_QUERY_USER_BY_NAME,data);

        if(responseEntity.getStatusCode() != HttpStatus.OK){
            dataFlowContext.setResponseEntity(responseEntity);
            return ;
        }

        JSONArray resultInfo = JSONObject.parseObject(responseEntity.getBody().toString()).getJSONArray("users");

        if(resultInfo != null || resultInfo.size() < 1){
            responseEntity = new ResponseEntity<String>(new JSONArray().toJSONString(),HttpStatus.OK);
            dataFlowContext.setResponseEntity(responseEntity);
            return ;
        }


    } 
                            #location 24 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void soService(ServiceDataFlowEvent event) throws ListenerExecuteException{


        DataFlowContext dataFlowContext = event.getDataFlowContext();
        AppService service = event.getAppService();
        JSONObject data = dataFlowContext.getReqJson();
        Assert.hasKeyAndValue(data,"storeId","请求报文中未包含storeId节点");
        Assert.hasKeyAndValue(data,"name","请求报文中未包含name节点");
        ResponseEntity<String> responseEntity = null;
        //根据名称查询用户信息
        responseEntity = super.callService(dataFlowContext,ServiceCodeConstant.SERVICE_CODE_QUERY_USER_BY_NAME,data);

        if(responseEntity.getStatusCode() != HttpStatus.OK){
            dataFlowContext.setResponseEntity(responseEntity);
            return ;
        }


        String useIds = getUserIds(responseEntity,dataFlowContext);
        if(StringUtil.isEmpty(useIds)){
            responseEntity = new ResponseEntity<String>(new JSONArray().toJSONString(),HttpStatus.OK);
            dataFlowContext.setResponseEntity(responseEntity);
            return ;
        }

        JSONArray userInfos = getUserInfos(responseEntity);
        Map<String,String> paramIn = new HashMap<>();
        paramIn.put("userIds",useIds);
        paramIn.put("storeId",data.getString("storeId"));
        //查询是商户员工的userId
        responseEntity = super.callService(dataFlowContext,ServiceCodeConstant.SERVICE_CODE_QUERY_STOREUSER_BYUSERIDS,paramIn);

        if(responseEntity.getStatusCode() != HttpStatus.OK){
            return ;
        }

        responseEntity = new ResponseEntity<String>(getStaffUsers(userInfos,responseEntity).toJSONString(),HttpStatus.OK);
        dataFlowContext.setResponseEntity(responseEntity);
    }