Flutter 具有全局键的可拖动包含对象

我有一个这样的拖鞋(a是StatefulWidget):

Draggable(child: a, feedback: a, childWhenDragging: null, data: a)

然而，a有一个GlobalKey，以在小部件被丢弃时保持状态.我的问题是，当您try 拖动时，会抛出duplicate GlobalKey错误(可能是因为child和feedback存在于同一帧上).有没有什么方法可以在没有任何错误的情况下实现这种行为？

可复制示例:

import 'package:flutter/material.dart';

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

class SFWidget extends StatefulWidget {
  const SFWidget({Key? key}) : super(key: key);
  @override
  State<SFWidget> createState() => SFWidgetState();
}

class SFWidgetState extends State<SFWidget> {
  String str = "str";
  @override
  Widget build(BuildContext context) {
    return Text(str);
  }

  void edit(String newstr) {
    setState(() {
      str = newstr;
    });
  }
}

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

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final key = GlobalKey<SFWidgetState>();
  final widget = SFWidget(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Draggable(
        child: widget,
        feedback: widget,
        data: widget,
        childWhenDragging: null,
      ),
    );
  }
}