CircleBorder Alert Dialog Box In Flutter Andorid App

Column(children: <Widget>[
  AlertDialog(
    backgroundColor: Colors.pink,
    title: Text("Alert Dialog",textAlign: TextAlign.center,style: TextStyle(color: Colors.white),),
    content: Text("Alert Dialog CircleBorder",textAlign: TextAlign.center,style: TextStyle(color: Colors.white)),
    contentPadding: EdgeInsets.all(60.0),
    shape: CircleBorder(),
  )
],)

import 'package:flutter/material.dart';

void main()
{
  runApp(MaterialApp(
    debugShowCheckedModeBanner: false,
    title: 'Androidmonks',
    home: FirstWidget(),
  ));
}
class FirstWidget extends StatelessWidget
{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
        appBar: AppBar(
          centerTitle: true,
          backgroundColor: Colors.black,
          title: Text("AndroidMonks"),),
        body: Column(children: <Widget>[
          AlertDialog(
            backgroundColor: Colors.pink,
            title: Text("Alert Dialog",textAlign: TextAlign.center,style: TextStyle(color: Colors.white),),
            content: Text("Alert Dialog CircleBorder",textAlign: TextAlign.center,style: TextStyle(color: Colors.white)),
            contentPadding: EdgeInsets.all(60.0),
            shape: CircleBorder(),
          )
        ],)
    );
  }

}