public Result send(Message msg, Route route) {
        return send(msg.setRoute(route));
    }
This is a convenience function to assign a given route to the given
message, and then pass it to the other {@link #send(Message)} method of
this session.

@param msg   the message to send
@param route the route to assign to the message
@return the immediate result of the attempt to send this message
messagebus/src/main/java/com/yahoo/messagebus/SourceSession.java