RepositoryStatePolicy not implemented

Hello, guys!

I'm developing vcs plugin and build trigger for it. ATM I'm experiencing the following error:
"RepositoryStatePolicy not implemented. See jetbrains.buildServer.vcs.ServerVcsSupport#getRepositoryStatePolicy"

The only place where I could find anything about getRepositoryStatePolicy method is this page. But I can't find any info about how to implement this method and why do I need it.

Please let me know where I can read about this method.

Best wishes,
Artyom