[api] refactor group_msg_to_json
[api] refactor group_msg_to_json

miurahr/seahub,miurahr/seahub,Chilledheart/seahub,cloudcopy/seahub,madflow/seahub,Chilledheart/seahub,Chilledheart/seahub,madflow/seahub,madflow/seahub,miurahr/seahub,Chilledheart/seahub,miurahr/seahub,madflow/seahub,madflow/seahub,cloudcopy/seahub,cloudcopy/seahub,Chilledheart/seahub,cloudcopy/seahub