public function getNewRegistrationIds()
    {
        if ($this->getNewRegistrationIdsCount() == 0) {
            return array();
        }
        $filteredResults = array_filter(
            $this->results,
            function ($result) {
                return isset($result['registration_id']);
            }
        );

        $data = array_map(function ($result) {
                return $result['registration_id'];
        }, $filteredResults);

        return $data;
    }