protected function registerMiddleware()
    {
        $this->app->singleton(\Develpr\AlexaApp\Http\Middleware\Request::class, function ($app) {
            return new \Develpr\AlexaApp\Http\Middleware\Request($app, $app['alexa.router'], $app['alexa.request'], $app['alexa.router.middleware']);
        });

        $this->app->singleton(\Develpr\AlexaApp\Http\Middleware\Certificate::class, function ($app) {
            return new \Develpr\AlexaApp\Http\Middleware\Certificate($app['alexa.request'], $app['alexa.certificateProvider'], $app['config']['alexa']);
        });
    }