Cleanup code in HST that assumes that a channel mgr site http session can 'survive' a cms logout

        HttpSession httpSession = containerRequest.getSession(false);

        // if the (HST) http session already exists, it might be because the user logged out from cms and logged in with
        // different user or logged in with same user again but the authorization rules for example changed (that is
        // why the user for example logged out and in). However, now it can happen that we have stale jcr sessions
        // still on the HttpSessionBoundJcrSessionHolder attribute of the HST http session. We need to clear these
        // now actively
        if (httpSession != null) {
            HttpSessionBoundJcrSessionHolder.clearAllBoundJcrSessions(HTTP_SESSION_ATTRIBUTE_NAME_PREFIX_CMS_PREVIEW_SESSION, httpSession);
        } else {
            httpSession = containerRequest.getSession(true);
        }