private void check() {
        boolean sidOk = false;
        if (sid != null && !sid.isEmpty()) {
            sidOk = true;
        }
        boolean serviceOk = false;
        if (service != null && !service.isEmpty()) {
            serviceOk = true;
        }

        if (!sidOk && !serviceOk) {
            throw new IllegalStateException();
        }
    }