WarmStandbyServerInfoGroup is used only with the Consumer.
The WarmStandbyServerInfoGroup contains a WarmStandbyServerInfoList, which contains one or more WarmStandbyServerInfo entries (each uniquely identified by a <Name …/> entry). Each warm standby server information is associated with a channel name and a set of preferred service names for service based warm standby.
When configuring for per-service based warm standby mode, the preferred service name set may be used to identify that channel as the starting channel for a given service.