Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Settings.php
public static function getLibXmlLoaderOptions()
    {
        if (self::$libXmlLoaderOptions === null && defined('LIBXML_DTDLOAD')) {
            self::setLibXmlLoaderOptions(LIBXML_DTDLOAD | LIBXML_DTDATTR);
        } elseif (self::$libXmlLoaderOptions === null) {
            self::$libXmlLoaderOptions = true;
        }

        return self::$libXmlLoaderOptions;
    }
public static function getLibXmlLoaderOptions()
    {
        if (self::$libXmlLoaderOptions === null && defined('LIBXML_DTDLOAD')) {
            self::setLibXmlLoaderOptions(LIBXML_DTDLOAD | LIBXML_DTDATTR);
        } elseif (self::$libXmlLoaderOptions === null) {
            self::$libXmlLoaderOptions = true;
        }

        return self::$libXmlLoaderOptions;
    }
Get default options for libxml loader.
Defaults to LIBXML_DTDLOAD | LIBXML_DTDATTR when not set explicitly.

@return int Default options for libxml loader