yii\filters\ContentNegotiator::negotiate PHP Метод

    public function negotiate()
    {
        $request = $this->request ?: Yii::$app->getRequest();
        $response = $this->response ?: Yii::$app->getResponse();
        if (!empty($this->formats)) {
            $this->negotiateContentType($request, $response);
        }
        if (!empty($this->languages)) {
            Yii::$app->language = $this->negotiateLanguage($request);
        }
    }