protected function registerHtmlMinifier()
    {
        $this->app->singleton('htmlmin.html', function (Container $app) {
            $css = $app['htmlmin.css'];
            $js = $app['htmlmin.js'];

            return new HtmlMinifier($css, $js);
        });

        $this->app->alias('htmlmin.html', HtmlMinifier::class);
    }