private function statusComparator($s1, $s2)
    {
        if (array_search($s1->getCode(), $this->statusOrder) === array_search($s2->getCode(), $this->statusOrder)) {
            return 0;
        }

        return (array_search($s1->getCode(), $this->statusOrder)
            < array_search($s2->getCode(), $this->statusOrder)) ? -1 : 1;
    }