截图所示报错？为什么？谢谢！

package com.mmall.common;

import java.io.Serializable;

import org.codehaus.jackson.map.annotate.JsonSerialize;

/**
* Created by kst on 2017/8/29.
*/
// 保证序列化json的时候,如果是null的对象,key也会消失
@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class ServerResponse<T> implements Serializable {
   /**
    * 返回状态
    */
   private int status;
   /**
    * 返回信息
    */
   private String msg;
   /**
    * 返回数据
    */
   private T data;

   private ServerResponse(int status) {
       this.status = status;
   }

   private ServerResponse(int status, String msg) {
       this.status = status;
       this.msg = msg;
   }

   // 使之不在json序列化结果当中
   public boolean isSuccess() {
       return this.status == ResponseCode.SUCCESS.getCode();
   }

   private ServerResponse(int status, T data) {
       this.status = status;
       this.data = data;
   }
   private ServerResponse(int status, String msg, T data) {
       this.status = status;
       this.msg = msg;
       this.data = data;
   }

   public int getStatus() {
       return status;
   }

   public T getData() {
       return data;
   }

   public String getMsg() {
       return msg;
   }

   // 成功情况
   public static <T> ServerResponse<T> createBySuccess() {
       return new ServerResponse<T>(ResponseCode.SUCCESS.getCode());
   }

   public static <T> ServerResponse<T> createBySuccessMessage(String msg) {
       return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(), msg);
   }

   public static <T> ServerResponse<T> createBySuccess(T data) {
       return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(), data);
   }

   public static <T> ServerResponse<T> createBySuccess(String msg, T data) {
       return new ServerResponse<T>(ResponseCode.SUCCESS.getCode(), msg, data);
   }

   // 失败情况
   public static <T> ServerResponse<T> createByError() {
       return new ServerResponse<T>(ResponseCode.ERROR.getCode(), ResponseCode.ERROR.getDesc());
   }

   public static <T> ServerResponse<T> createByErrorMessage(String errorMessage) {
       return new ServerResponse<T>(ResponseCode.ERROR.getCode(), errorMessage);
   }

   public static <T> ServerResponse<T> createByErrorCodeMessage(int errorCode, String errorMessage) {
       return new ServerResponse<T>(errorCode, errorMessage);
   }
}