this.pomOrder = pomOrder;
    }
    // ----------------------------------------------------------------------------
    /**
     * helper for equals
     */
    private static boolean objectsEqual(Object o1, Object o2) {
        if (o1 == null && o2 == null) {
            return true;
        }
        if (o1 == null || o2 == null) {
            return false; // as they are not both null
        }