... you have to be carefull using comercial version name EAP 6 :-) on community forum :-)
some peoples will strongly advice you to call redhat support, even if they know the solution.
You need this patch from redhat support portal ( EAP 6.0.0 ):
[EAP6] UnsupportedCallbackException where security realm delegates to JAAS realm.
https://access.redhat.com/jbossnetwork/restricted/softwareDownload.html?softwareId=14083
You need commercial subscription to get this.