public function findWorkspaceRootsByRoles(array $roles)
    {
        $builder = new ResourceQueryBuilder();
        $dql = $builder->selectAsArray()
            ->whereParentIsNull()
            ->whereHasRoleIn($roles)
            ->orderByName()
            ->getDql();

        $query = $this->_em->createQuery($dql);
        $query->setParameters($builder->getParameters());

        return $this->executeQuery($query);
    }