public function getInstalledHandles()
    {
        $query = 'select p.pkgHandle from \\Concrete\\Core\\Entity\\Package p';
        $r = $this->entityManager->createQuery($query);
        $result = $r->getArrayResult();
        $handles = [];
        foreach ($result as $r) {
            $handles[] = $r['pkgHandle'];
        }

        return $handles;
    }