Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Style/Borders.php
public function setDiagonalDirection($pValue)
    {
        if ($pValue == '') {
            $pValue = self::DIAGONAL_NONE;
        }
        if ($this->isSupervisor) {
            $styleArray = $this->getStyleArray(['diagonalDirection' => $pValue]);
            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($styleArray);
        } else {
            $this->diagonalDirection = $pValue;
        }

        return $this;
    }
public function setDiagonalDirection($pValue)
    {
        if ($pValue == '') {
            $pValue = self::DIAGONAL_NONE;
        }
        if ($this->isSupervisor) {
            $styleArray = $this->getStyleArray(['diagonalDirection' => $pValue]);
            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($styleArray);
        } else {
            $this->diagonalDirection = $pValue;
        }

        return $this;
    }
Set DiagonalDirection.

@param int $pValue see self::DIAGONAL_*

@return Borders