WebviewScaffold with basic auth - how to Post request with parameters

Question

I am loading a web page with basic authentication like this:

@override
 Widget build(BuildContext context) {
   return new WebviewScaffold(
     appBar: new AppBar(
         title: new Text(“Web View”),
         centerTitle: true,
         backgroundColor: Colors.red[900],
         elevation: 0.0,
     ),
     url: widget.url,
     withJavascript: true,
     withZoom: false,
     clearCookies: true,
     headers: {‘Authorization’: ‘Basic ’ + base64Encode(utf8.encode(‘$widget.user:$widget.pass’))},
   );
 }

For another url, I want to make a post request and send parameters, is it possible with WebviewScaffold?