For realms like the TokenSecurityRealm where we rely on Evidence we don't have an opportunity to use pre-realm principal transformers to adjust the principal as seen by the underlying deployed application.

This security realm does contain a claimToPrincipal function that maybe could be used for this purpose but in WildFly we don't presently expose this to end users, additionally this is a different API to all other mappers we currently expose.

This feature request is to add support for a principal transformer to be provided to the realm that will be applied after the claimToPrincipal mapping is performed.