What are the rules for C++ callback servers calling Finish?

[Jeffrey Baker]

In a C++ callback-style server, what are the defined semantics for the context in which Finish is called on the reactor? If I call it from my application's own thread, how does it behave? Is it possible that it will do network I/O on the calling thread, or does Finish always emplace the notification for one of gRPC's own threads to handle? Or, are the consequences not defined?

I read https://github.com/grpc/proposal/pull/180/files and some of the source code but that didn't clear it up for me.

-Jeff