解决spring mvc 返回json数据到ajax报错parseerror问题

$.ajax({ 
      type: 'POST', 
      url: "groupFunctionEdit", 
      dataType: 'json', 
      contentType: "application/json", 
      data: JSON.stringify(functiondata), 
      success: function(data){ 
        alert('数据加载成功'+data.msg); 
      }, 
      error: function(xhr, type){ 
        alert('数据加载失败'); 
        console.log(type); 
      } 

@RequestMapping("/groupFunctionEdit")   
  public @ResponseBody Object groupFunctionEdit(@RequestBody List<YyGroupFunction> yyGroupFunctionList) throws JsonProcessingException{ 
     
    return "success"; 
  } 

@RequestMapping("/groupFunctionEdit")   
  public @ResponseBody Object groupFunctionEdit(@RequestBody List<YyGroupFunction> yyGroupFunctionList) throws JsonProcessingException{ 
     Map<String,Object> map = new HashMap<String,Object>(); 
     map.put("msg", "success"); 
     ObjectMapper mapper = new ObjectMapper(); 
     String msg = mapper.writeValueAsString(map); 
    return msg; 
  } 

{"msg":"success"}