public function loadByIdentifier($identifier, $groupId)
    {
        $data = $this->objectStateGateway->loadObjectStateDataByIdentifier($identifier, $groupId);

        if (empty($data)) {
            throw new NotFoundException('ObjectState', array('identifier' => $identifier, 'groupId' => $groupId));
        }

        return $this->objectStateMapper->createObjectStateFromData($data);
    }