Sonata\Exporter\Writer\XmlExcelWriter::getXmlString PHP Method

    private function getXmlString(array $fields = array())
    {
        $xmlData = array();
        $xmlData[] = '<Row>';
        foreach ($fields as $key => $value) {
            $value = htmlspecialchars($value);
            $value = str_replace(array("\r\n", "\r", "\n"), '&#10;', $value);
            $dataType = 'String';
            if ($this->position != 0 || !$this->showHeaders) {
                $dataType = $this->getDataType($key, $value);
            }
            $xmlData[] = '<Cell><Data ss:Type="' . $dataType . '">' . $value . '</Data></Cell>';
        }
        $xmlData[] = '</Row>';
        return implode('', $xmlData);
    }