MultiSliver has wrong behavior with center key - sliver_tools: 0.2.6

main.dart

import 'package:flutter/material.dart';
import 'package:sliver_tools/sliver_tools.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: DemoApp(),
    );
  }
}

class DemoApp extends StatefulWidget {
  const DemoApp({Key? key}) : super(key: key);

  @override
  _DemoAppState createState() => _DemoAppState();
}

class _DemoAppState extends State<DemoApp> {
  bool multiSliverEnabled = true;

  List<int> top = List<int>.generate(10, (i) => -(i));
  List<int> bottom = List<int>.generate(10, (i) => i + 1);

  @override
  Widget build(BuildContext context) {
    const Key centerKey = ValueKey('second-sliver-list');
    return Scaffold(
      appBar: AppBar(
        title: const Text('Press Button to Toggle MultiSliver'),
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () {
          setState(() {
            multiSliverEnabled = !multiSliverEnabled;
          });
        },
        label: Text('MultiSliver: $multiSliverEnabled'),
      ),
      body: CustomScrollView(
        center: centerKey,
        slivers: <Widget>[
          if (multiSliverEnabled) ...[
            MultiSliver(
              children: [_buildTopList()],
            ),
            MultiSliver(
              key: centerKey,
              children: [_buildBottomList()],
            ),
          ] else ...[
            _buildTopList(),
            _buildBottomList(centerKey),
          ]
        ],
      ),
    );
  }

  Widget _buildBottomList([Key? centerKey]) {
    return SliverList(
      key: centerKey,
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          return Container(
            alignment: Alignment.center,
            color: Colors.blue.shade200,
            child: Text('Item: ${bottom[index]}'),
          );
        },
        childCount: bottom.length,
      ),
    );
  }

  Widget _buildTopList() {
    return SliverList(
      delegate: SliverChildBuilderDelegate(
        (BuildContext context, int index) {
          return Container(
            alignment: Alignment.center,
            color: Colors.green.shade200,
            child: Text('Item: ${top[index]}'),
          );
        },
        childCount: top.length,
      ),
    );
  }
}