public static function setDefaultLicense(array $license)
    {
        if (!array_key_exists('name', $license) || !array_key_exists('key', $license)) {
            throw new Exception\InvalidArgumentException(__METHOD__ . " In order to set a default libxl license you must provide an associative array with 'name' and 'key' set.");
        }

        self::$default_license = $license;
    }