public function fetchRequestToken(array $params = [])
    {
        $this->setAccessToken(null);
        $defaultParams = [
            'oauth_consumer_key' => $this->consumerKey,
            'oauth_callback' => $this->getReturnUrl(),
            //'xoauth_displayname' => Yii::$app->name,
        ];
        if (!empty($this->scope)) {
            $defaultParams['scope'] = $this->scope;
        }

        $request = $this->createRequest()
            ->setMethod($this->requestTokenMethod)
            ->setUrl($this->requestTokenUrl)
            ->setData(array_merge($defaultParams, $params));

        $this->signRequest($request);

        $response = $this->sendRequest($request);

        $token = $this->createToken([
            'params' => $response
        ]);
        $this->setState('requestToken', $token);

        return $token;
    }