class SessionScopeExtractor implements AttributeExtractor {

    @SuppressWarnings("unchecked")
    @Override
    public Enumeration<String> getKeys() {
        HttpSession session = request.getSession(false);
        if (session != null) {
            return session.getAttributeNames();
        }
        return Collections.enumeration(Collections.<String>emptySet());
    }

    public  SessionScopeExtractor(HttpServletRequest request);

}