undertow/src/main/java/org/wildfly/extension/undertow/security/jaspi/JASPICSecurityContext.java
private Subject getAuthenticatedSubject() {
        Subject subject = null;
        org.jboss.security.SecurityContext picketBoxContext = SecurityActions.getSecurityContext();
        if (picketBoxContext != null && picketBoxContext.getSubjectInfo() != null)
            subject = picketBoxContext.getSubjectInfo().getAuthenticatedSubject();
        return subject != null ? subject : new Subject();
    }
private Subject getAuthenticatedSubject() {
        Subject subject = null;
        org.jboss.security.SecurityContext picketBoxContext = SecurityActions.getSecurityContext();
        if (picketBoxContext != null && picketBoxContext.getSubjectInfo() != null)
            subject = picketBoxContext.getSubjectInfo().getAuthenticatedSubject();
        return subject != null ? subject : new Subject();
    }
<p>
Retrieves the authenticated subject from the underlying security context.
</p>

@return a reference to the authenticated subject.