Verified in EAP 6.4.7.CP.CR2.
Due to bug in Apache Harmony with IBM JDK 1.6 [1] expected role with '/' character is still not assigned to user. However fix of this BZ causes that authentication can proceed and does not fail with IllegalArgumentException (caused by Apache Harmony bug).
[1] https://issues.apache.org/jira/browse/HARMONY-4229