RFBridge - Change the MQTT gateway name

In documentation is written that we can change the name of a gateway without limitations. By comparison for " Change the MQTT broker credentials" here is a written limitation for RFBridge.
In my case (compile by myself) the change is valid until restart. Should I use the
build_flags = '-UMQTTsetMQTT' if I want to change something of RFBridge?
Thank you