Custom BottomNavigationBar in Flutter

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage()
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(child: Text('Hello World')),
      floatingActionButton: FloatingActionButton(onPressed: (){}, child: Icon(Icons.add)),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        color: Colors.blue,
        shape: CircularNotchedRectangle(),
        child: Container(
          height: 80,
          child: Padding(
            padding: const EdgeInsets.symmetric(horizontal: 20.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: <Widget>[
              Icon(Icons.home, size: 40.0, color: Colors.white),
              Icon(Icons.school, size: 40.0, color: Colors.white),
              SizedBox.shrink(),
              Icon(Icons.business_center, size: 40.0, color: Colors.white),
              Icon(Icons.contact_phone, size: 40.0, color: Colors.white)
            ],),
          )
        )
      ),
    );
  }
}