Java SDK 如何获取到cn.leancloud.Messages中ErrorCommand的appMsg字段

peerId: "2353492"
i: -65508
service: 2
ackMessage {
code: 4402
reason: "MESSAGE_REJECTED_BY_APP"
t: 1592477090827
uid: "cLcswzKpTDGzwlZc5R5UBQ"
appCode: 101
appMsg: "msg"
}