Pedro Epicor 10.1.600 - Epicor.System.dll
It’s for use in a BPM, because of the issue with namespace clashing if you have two different assemblies referencing the same tablesets. I’ve looked for it in the server before but I don’t see it there. I’ve only found it in the clients.
Specific code is:
private Lazy _db = new Lazy(() => CallContext.Current.GetMainContext());