This group is used to override WarningMonitor targetted to Exchange 2015 HelathSets.Member healthsets will generate only warning alerts and will have warning unhealthy states.
<ClassType ID="Microsoft.Exchange.15.Custom.WarningHealthSets.Group" Accessibility="Public" Abstract="false" Base="MSIL!Microsoft.SystemCenter.InstanceGroup" Hosted="false" Singleton="true" Extension="false"/>