protected function prepareCacheLabels()
    {
        $export = $this->exportManager->getExport($this->exportAlias);
        $keys = $export->getQueryKeys($this->exportData);
        
        foreach($keys as $key) {
            // get an array with all values for this key if possible
            $values = \array_map(function ($v) use ($key) { return $v[$key]; }, $this->result);
            // store the label in the labelsCache property
            $this->labelsCache[$key] = $export->getLabels($key, $values, $this->exportData);
        }
    }