Returns the Room Group name.
SmartFox2X (in SmartFox2X.dll) Version: 18.104.22.168 (1.7.11)
Each Group is identified by a unique string (its name or id) and it represents a different "container" for Rooms.
Room Groups enable developers to organize Rooms under different types or categories and let clients select only those Groups they are interested in,
in order to receive their events only. This is done via the SubscribeRoomGroupRequest
The default value is default