Nord\Lumen\Cors\CorsService::isHeaderAllowed PHP Метод

    protected function isHeaderAllowed($header)
    {
        if (!$header) {
            throw new InvalidArgument('Header cannot be empty.');
        }
        if ($this->isAllHeadersAllowed()) {
            return true;
        }
        return in_array(strtolower($header), $this->allowHeaders);
    }