Global RailClientContext::ServerHandshake: before 3.27.0 the response was sent before this callback was invoked. Now the default implementation provides this and if overridden by client implementations they must handle the response themselves.
Global RailClientContext::ServerHandshakeEx: before 3.27.0 the response was sent before this callback was invoked. Now the default implementation provides this and if overridden by client implementations they must handle the response themselves.