Neomerx\JsonApi\Http\Headers\HeaderParametersParser::getHeader PHP Метод

    private function getHeader(ServerRequestInterface $request, $name)
    {
        $value = $request->getHeader($name);
        if (empty($value) === false) {
            $value = $value[0];
            if (empty($value) === false) {
                return $value;
            }
        }
        return MediaTypeInterface::JSON_API_MEDIA_TYPE;
    }