为什么无法获取message 的JSONObjec属性 哪位大神帮看一下

chat listener receive msg from:admin@easemob.com body:{"from":"admin","to":"u_13800138004","bodies":[{"msg":"李17申请加入09 的群组","type":"txt"}],"ext":{"messageType":4,"messageId":null}}

但是提示 unknow additonal msg attr:org.json.JSONObject$1
com.easemob.exceptions.EaseMobException: attribute ext not found