FocusScope.of(context).requestFocus(new MyFocusNode()) memleak test

focus_node_mem_leak_test.dart

import 'package:flutter/material.dart';

class MyFocusNode extends FocusNode {
  MyFocusNode() : super() {
    print("constructor");
  }

  @override
  void dispose() {
    print("dispose");
    super.dispose();
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark(),
      debugShowCheckedModeBanner: false,
      home: Screen1(),
    );
  }
}

class Screen1 extends StatefulWidget {
  @override
  _Screen1State createState() => _Screen1State();
}

class _Screen1State extends State<Screen1> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              child: Text("unfocus"),
              onPressed: () =>
                  FocusScope.of(context).requestFocus(new MyFocusNode()),
            ),
            RaisedButton(
              child: Text("next page"),
              onPressed: () => Navigator.of(context).pushReplacement(
                MaterialPageRoute(builder: (ctx) => Screen2()),
              ),
            )
          ],
        ),
      ),
    );
  }

  @override
  void dispose() {
    print("dispose screen1");
    super.dispose();
  }
}

class Screen2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: RaisedButton(
          child: Text("go back"),
          onPressed: () => Navigator.of(context).pushReplacement(
            MaterialPageRoute(builder: (ctx) => Screen1()),
          ),
        ),
      ),
    );
  }
}