RD Connection Broker 2012 - needed documentation to implement a plugin

Hello,

I am trying to implement a plugin for RD Connection Broker (by using of realization of the IWTSSBPlugin interface)
In documentation I have readed that I should register my plugin in ExtensibilityPluginCLSID parameter (of the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tssdis\Parameters registry key)

But when I look into trace of tssdis.exe (by ProcessMonitor) then I can't see any accesses to this parameter. Instead of that I see access to other parameters of this registry key - DbPluginClsid, DbObjectFactoryClsid, ConnectionOrchRunningVmTimeout etc.
Also I see the "Plugins" subkey in this registry key and I see access to this subkey. But I can not find any chapters in MSDN about these parameters and subkey.

I think the mentioned documentation was written for older version of Windows Server. Please help me find a newer documents about implementation of plugin(s) for RD Connection Broker 2012

Thank you