Flutter setState() not refreshing widget when called from stateful child - flutter

Question

I have two stateful widgets: ParentWidget and ChildWidget.
The ChildWidget has a gesture detector wrapping a container and text. When I call onTap the state of the Parent (status increased by 1) is updated properly but setState() is not refreshing the UI.
I tried everything: global keys, inherited widget but nothing works.
Interestingly if I change the ChildWidget to a stateless one then everything start working. Any ideas would be super helpful.
pk
Here is the code:
import 'package:flutter/material.dart';
import 'package:hexcolor/hexcolor.dart';
class ParentWidget extends StatefulWidget {
#override
_ParentWidgetState createState() => _ParentWidgetState();
}
class _ParentWidgetState extends State<ParentWidget> {
int status = 1;
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
appBar: AppBar(
backgroundColor: Hexcolor('#1c486d'),
title: Text(
'Test',
),
),
body: ChildWidget(
child: GestureDetector(
onTap: () {
status = status + 1;
setState(() {}); // this is the problematic piece of code.
},
child: Container(
color: Colors.blue,
width: 100,
height: 100,
child: Text('PARENT:' + status.toString()),
),
),
),
);
}
}
class ChildWidget extends StatefulWidget {
final Widget child;
ChildWidget({this.child});
#override
_ChildWidgetState createState() => _ChildWidgetState(child);
}
class _ChildWidgetState extends State<ChildWidget> {
Widget child;
_ChildWidgetState(this.child);
#override
Widget build(BuildContext context) {
return child;
}
}

Answer 1

You can pass the parent's status to the ChildWidget so that when the parent's status changes, the ChildWidget's state changes and its build method be called.
body: GestureDetector(
onTap: () {
setState(() {
status = status + 1;
});
},
child: ChildWidget(status: status),
),
);
}
}
class ChildWidget extends StatefulWidget {
final int status;
ChildWidget({this.status});
#override
_ChildWidgetState createState() => _ChildWidgetState();
}
class _ChildWidgetState extends State<ChildWidget> {
_ChildWidgetState();
#override
Widget build(BuildContext context) {
return Container(
color: Colors.blue,
width: 100,
height: 100,
child: Text('PARENT:' + widget.status.toString()),
);
}
}

Answer 2

Try not making the child final
class ChildWidget extends StatefulWidget {
Widget child;
ChildWidget({this.child});
#override
_ChildWidgetState createState() => _ChildWidgetState(child);
}