protected static function _exportMetrics($xmlDocument, $metrics)
    {
        $data = $metrics->data();
        $xmlMetrics = $xmlDocument->createElement('metrics');
        $xmlMetrics->setAttribute('loc', $data['loc']);
        $xmlMetrics->setAttribute('ncloc', $data['nlloc']);
        $xmlMetrics->setAttribute('statements', $data['lloc']);
        $xmlMetrics->setAttribute('coveredstatements', $data['cloc']);
        return $xmlMetrics;
    }