Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xlsx/Style.php
private function writeBorder(XMLWriter $objWriter, Borders $pBorders)
    {
        // Write border
        $objWriter->startElement('border');
        // Diagonal?
        switch ($pBorders->getDiagonalDirection()) {
            case Borders::DIAGONAL_UP:
                $objWriter->writeAttribute('diagonalUp', 'true');
                $objWriter->writeAttribute('diagonalDown', 'false');

                break;
            case Borders::DIAGONAL_DOWN:
                $objWriter->writeAttribute('diagonalUp', 'false');
                $objWriter->writeAttribute('diagonalDown', 'true');

                break;
            case Borders::DIAGONAL_BOTH:
                $objWriter->writeAttribute('diagonalUp', 'true');
                $objWriter->writeAttribute('diagonalDown', 'true');

                break;
        }

        // BorderPr
        $this->writeBorderPr($objWriter, 'left', $pBorders->getLeft());
        $this->writeBorderPr($objWriter, 'right', $pBorders->getRight());
        $this->writeBorderPr($objWriter, 'top', $pBorders->getTop());
        $this->writeBorderPr($objWriter, 'bottom', $pBorders->getBottom());
        $this->writeBorderPr($objWriter, 'diagonal', $pBorders->getDiagonal());
        $objWriter->endElement();
    }
private function writeBorder(XMLWriter $objWriter, Borders $pBorders)
    {
        // Write border
        $objWriter->startElement('border');
        // Diagonal?
        switch ($pBorders->getDiagonalDirection()) {
            case Borders::DIAGONAL_UP:
                $objWriter->writeAttribute('diagonalUp', 'true');
                $objWriter->writeAttribute('diagonalDown', 'false');

                break;
            case Borders::DIAGONAL_DOWN:
                $objWriter->writeAttribute('diagonalUp', 'false');
                $objWriter->writeAttribute('diagonalDown', 'true');

                break;
            case Borders::DIAGONAL_BOTH:
                $objWriter->writeAttribute('diagonalUp', 'true');
                $objWriter->writeAttribute('diagonalDown', 'true');

                break;
        }

        // BorderPr
        $this->writeBorderPr($objWriter, 'left', $pBorders->getLeft());
        $this->writeBorderPr($objWriter, 'right', $pBorders->getRight());
        $this->writeBorderPr($objWriter, 'top', $pBorders->getTop());
        $this->writeBorderPr($objWriter, 'bottom', $pBorders->getBottom());
        $this->writeBorderPr($objWriter, 'diagonal', $pBorders->getDiagonal());
        $objWriter->endElement();
    }
Write Border.

@param XMLWriter $objWriter XML Writer
@param Borders $pBorders Borders style