public function writeComments(\PhpOffice\PhpSpreadsheet\Worksheet\Worksheet $pWorksheet)
    {
        // Create XML writer
        $objWriter = null;
        if ($this->getParentWriter()->getUseDiskCaching()) {
            $objWriter = new XMLWriter(XMLWriter::STORAGE_DISK, $this->getParentWriter()->getDiskCachingDirectory());
        } else {
            $objWriter = new XMLWriter(XMLWriter::STORAGE_MEMORY);
        }

        // XML header
        $objWriter->startDocument('1.0', 'UTF-8', 'yes');

        // Comments cache
        $comments = $pWorksheet->getComments();

        // Authors cache
        $authors = [];
        $authorId = 0;
        foreach ($comments as $comment) {
            if (!isset($authors[$comment->getAuthor()])) {
                $authors[$comment->getAuthor()] = $authorId++;
            }
        }

        // comments
        $objWriter->startElement('comments');
        $objWriter->writeAttribute('xmlns', 'http://schemas.openxmlformats.org/spreadsheetml/2006/main');

        // Loop through authors
        $objWriter->startElement('authors');
        foreach ($authors as $author => $index) {
            $objWriter->writeElement('author', $author);
        }
        $objWriter->endElement();

        // Loop through comments
        $objWriter->startElement('commentList');
        foreach ($comments as $key => $value) {
            $this->writeComment($objWriter, $key, $value, $authors);
        }
        $objWriter->endElement();

        $objWriter->endElement();

        // Return
        return $objWriter->getData();
    }