Currently, there exists a RolesRegistry implementation under uf-ext.

https://github.com/porcelli-forks/uberfire-extensions/blob/2de657fea45fa0669d65876f734f305745b69000/uberfire-security/uberfire-servlet-security/src/main/java/org/uberfire/ext/security/server/RolesRegistry.java

At the time of this writing, it is up to every single uf application to register the roles during. The goal is get rid of that and to delegate to the uf core the initialization of the RoleRegistry with the roles declared into the web.xml descriptor since those are the only roles valid to the UF's authentication & authorization services. For non web environments, the RoleRegistry will remain empty unless someone provides the required roles.