private function getAcl(): ?array {

		if (!$this->issetCache('acl')) {
		
			$query =
				'SELECT r.*, m.name AS module_name' .
				' FROM `rules` AS r' .
				' INNER JOIN `acl` AS a ON a.rule_id = r.id'.
				' INNER JOIN `modules` AS m ON r.module_id = m.id'.
				' WHERE a.group_id = ?';
			
			$this->db->setQuery($query);
			$this->setCache('acl', $this->db->loadObjectList($this->groupId));

		}

		return $this->getCache('acl');
		
	}