Post your -aop.xml configs where you have added your custom interceptor.
By the way, I would recommend that it's better to not rely on JBoss internal classes.
Intention to use AOP interceptor was not to get to caller principal.It is written for getting context data passed by client which are generic and not specific to bean method call(e.g Locale)
Can't it be done through javax.interceptor.* interceptors?