Description of problem: trying to log out- throws exception

Version-Release number of selected component (if applicable): 6.0.3

How reproducible:

Steps to Reproduce:
1. login into Business0central
2. log out
3.

Actual results: supposed log-out with any error

Expected results: throws exception

Additional info:
JBWEB000309: type JBWEB000066: Exception report

JBWEB000068: message attempting to add an object which is not an instance of java.security.Principal to a Subject's Principal Set

JBWEB000069: description JBWEB000145: The server encountered an internal error that prevented it from fulfilling this request.

JBWEB000070: exception

java.lang.SecurityException: attempting to add an object which is not an instance of java.security.Principal to a Subject's Principal Set
javax.security.auth.Subject$SecureSet.add(Subject.java:1072)
java.util.Collections$SynchronizedCollection.add(Collections.java:1577)
org.apache.catalina.connector.Request.setUserPrincipal(Request.java:2035)
org.apache.catalina.authenticator.AuthenticatorBase.unregister(AuthenticatorBase.java:712)
org.apache.catalina.authenticator.AuthenticatorBase.logout(AuthenticatorBase.java:343)
org.apache.catalina.connector.Request.logout(Request.java:3243)
org.apache.catalina.connector.RequestFacade.logout(RequestFacade.java:1018)
org.uberfire.security.server.auth.HttpAuthenticationManager.logout(HttpAuthenticationManager.java:198)
org.uberfire.security.server.HttpSecurityManagerImpl.logout(HttpSecurityManagerImpl.java:207)
org.uberfire.security.server.UberFireSecurityFilter.logout(UberFireSecurityFilter.java:283)
org.uberfire.security.server.UberFireSecurityFilter.doFilter(UberFireSecurityFilter.java:259)
sun.reflect.GeneratedMethodAccessor288.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:263)
org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:261)
java.security.AccessController.doPrivileged(Native Method)
javax.security.auth.Subject.doAsPrivileged(Subject.java:515)
org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:295)
org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:236)