TabBar text not getting updated inside NestedScrollView on setState - flutter

Question

In my real project, I'm using TabBar inside SliverPersistentHeader which is wrapped with NestedScrollView. The problem is when I call setState(() {}) the text doesn't update. Tough the actual value is updated. The text gets updated only when I perform scroll.
I know Tab is a const constructor and it is not supposed to be rebuilt on setState(() {}), however, when I run the same example without NestedScrollView and SliverPersistentHeader and the TabBar in AppBar it works as expected.
I've written a demo project showcasing the problem.
main.dart
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage>
with SingleTickerProviderStateMixin {
int _counter = 0;
TabController _tabController;
ScrollController _scrollController;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
void initState() {
_tabController = TabController(length: 1, vsync: this);
_scrollController = ScrollController();
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Tabs Demo'),
),
body: NestedScrollView(
controller: _scrollController,
headerSliverBuilder: (context, innerBoxIsScrolled) {
print('$_counter');
return [
SliverPersistentHeader(
pinned: true,
delegate: SliverPersistentHeaderDelegateImpl(
tabBar: TabBar(
controller: _tabController,
labelColor: Colors.black,
tabs: [
Tab(
text: 'Tab $_counter',
)
],
),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(5.0),
boxShadow: [
BoxShadow(
color: Colors.grey[350],
offset: Offset(0.0, 1.0),
blurRadius: 0),
],
),
),
)
];
},
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
class SliverPersistentHeaderDelegateImpl
extends SliverPersistentHeaderDelegate {
final TabBar tabBar;
final Decoration decoration;
const SliverPersistentHeaderDelegateImpl({
this.decoration,
#required this.tabBar,
});
#override
Widget build(
BuildContext context, double shrinkOffset, bool overlapsContent) {
return Container(
child: tabBar,
decoration: decoration,
);
}
#override
double get maxExtent => tabBar.preferredSize.height;
#override
double get minExtent => tabBar.preferredSize.height;
#override
bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate) {
return false;
}
}