public function tokenAction(Request $request)
    {
        /** @var PropertyAccess $config */
        $config = $this->app['conf'];

        if ( ! $request->isSecure() && $config->get(['main', 'api_require_ssl'], true) == true) {
            throw new HttpException(400, 'This route requires the use of the https scheme: ' . $config->get(['main', 'api_require_ssl']), null, ['content-type' => 'application/json']);
        }

        $this->oAuth2Adapter->grantAccessToken();
        ob_flush();
        flush();

        // As OAuth2 library already outputs response content, we need to send an empty
        // response to avoid breaking silex controller
        return '';
    }