JObject obj = new JObject(
new JProperty(JsonKey.O_TYPE, chat.O_type),
new JProperty(JsonKey.CONTENT, new JObject(
new JProperty(JsonKey.FULLID, chat.Fullid),
new JProperty(JsonKey.CHAT_GROUP_NAME, chat.Chat_group_name)
)));
如:当FULLID可选时,应该怎么组装呢?