Snakeyaml：无法为其创建属性

如何解决Snakeyaml：无法为其创建属性

我有一个Yaml文件作为参数传递给java类。但这引发了以下异常：

日志

   class DeliveryTimeline extends StatefulWidget {
      DeliveryTimeline({Key key,this.title}) : super(key: key);
    
      final String title;
    
      @override
      _MyHomePageState createState() => new _MyHomePageState();
    }
    
    class _MyHomePageState extends State<DeliveryTimeline> {
      int _currentStep = 0;
      String shippingtype;
    
      @override
      Widget build(BuildContext context) {
        return new Scaffold(
            appBar: AppBar(
              backgroundColor: Colors.white,centerTitle: true,iconTheme: new IconThemeData(color: Colors.black),elevation: 0,title: Text(
                "Checkout",style: TextStyle(color: Colors.black),),body: Stepper(
                type: StepperType.horizontal,steps: _mySteps(),currentStep: this._currentStep,onStepTapped: (step) {
                  setState(() {
                    this._currentStep = step;
                  });
                },onStepContinue: () {
                  setState(() {
                    if (this._currentStep == 0) {
                      this._currentStep = this._currentStep + 1;

**//need to get value here on first next click**

                    } else if (this._currentStep == 1) {
                      this._currentStep = this._currentStep + 1;
                    } else {
                      print('Completed,check fields.');
                    }
    
                  });
                },onStepCancel: () {
                  setState(() {
                    if (this._currentStep > 0) {
                      this._currentStep = this._currentStep - 1;
                    } else {
                      this._currentStep = 0;
                    }
                  });
                },controlsBuilder: (BuildContext context,{VoidCallback onStepContinue,VoidCallback onStepCancel,Function onShippingNextClick}) {
                  return Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,children: <Widget>[
                      OutlineButton(
                          child: new Text("Back"),onPressed: onStepCancel,shape: new RoundedRectangleBorder(
                              borderRadius: new BorderRadius.circular(4.0))),MaterialButton(
                        child: Text("Next"),color: AppColors.primarycolor,textColor: Colors.white,onPressed: onStepContinue,],);
                }));
      }
    
      List<Step> _mySteps() {
        List<Step> _steps = [
          Step(
            title: Text('Delivery'),content: Center(
              child: Container(
                height: MediaQuery.of(context).size.height / 1.5,child: Delivery(onShipingTypeClicked: (shippingtype){
                  shippingtype = shippingtype;
                  print("myvalue${shippingtype}");
                },isActive: _currentStep >= 0,Step(
            title: Text('Address'),content: Address(),isActive: _currentStep >= 1,Step(
            title: Text('Payment'),content: Payment(),isActive: _currentStep >= 2,)
        ];
        return _steps;
      }
    
    
    }

我的分析：

1. MyClass打包为jar，它可用于另一个项目，所以我的yaml文件应该有问题。
2. Yaml验证已通过，似乎所有变量都使用camelCase。
3. 根据我的发现，如果属性值为null（不是按日志记录）和isWritable（我没有获得此部分），PropertyUtils会进行2次检查以引发此异常。
4. 对于jdbcDriverClassString，错误指示在名称上，对于heartbeatThreshold值，其指示在值上。

能帮我解决一下吗？我将非常感谢。

Yaml文件：

class Delivery extends StatefulWidget {
  final ValueChanged<String> onShipingTypeClicked;

   Delivery({this.onShipingTypeClicked});

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

class _DeliveryState extends State<Delivery> {

  List<RadioModel> sampleData = new List<RadioModel>();




  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    sampleData.add(new RadioModel(false,'A',0xffe6194B,"Standard Delivery","Order will be delivered between 3 - 5 business days",1));
    sampleData.add(new RadioModel(
        true,"Next Day Delivery","Place your order before 6pm and your items will be delivered the next day",2));
    sampleData.add(new RadioModel(
        false,"Nominated Delivery","Pick a particular date from the calendar and order will be delivered on selected date",3));


  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new ListView.builder(
        itemCount: sampleData.length,shrinkWrap: true,physics: NeverScrollableScrollPhysics(),itemBuilder: (BuildContext context,int index) {
          return new InkWell(
              onTap: () {
                setState(() {
                  sampleData.forEach((element) => element.isSelected = false);
                  sampleData[index].isSelected = true;
                  widget.onShipingTypeClicked(sampleData[index].buttonText);
                });
              },child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,children: <Widget>[
                  TextSmallTitleSize(
                    title: sampleData[index].title,Padding(
                    padding: const EdgeInsets.only(bottom: 20.0),child: Row(
                      mainAxisAlignment: MainAxisAlignment.spaceAround,children: <Widget>[
                        Flexible(
                          child: TextSmallDimText(sampleData[index].label),RadioItem(sampleData[index]),)
                ],));
        },);
  }
}

class RadioItem extends StatelessWidget {
  final RadioModel _item;

  RadioItem(this._item);

  @override
  Widget build(BuildContext context) {
    return new Container(
      margin: new EdgeInsets.all(15.0),child: new Row(
        mainAxisSize: MainAxisSize.max,children: <Widget>[
          new Container(
            height: 25.0,width: 25.0,alignment: Alignment.center,child: Container(
                height: 15.0,width: 15.0,decoration: new BoxDecoration(
                  color: AppColors.primarycolor,borderRadius:
                      const BorderRadius.all(const Radius.circular(15)),)),decoration: new BoxDecoration(
              color: Colors.transparent,border: new Border.all(
                  width: 3.0,color: _item.isSelected
                      ? AppColors.primarycolor
                      : Colors.transparent),borderRadius: const BorderRadius.all(const Radius.circular(25)),new Container(margin: new EdgeInsets.only(left: 10.0))
        ],);
  }
}

class RadioModel {
  bool isSelected;
  final String buttonText;
  final int colorCode;
  final String title,label;
  final int buttonid;

  RadioModel(this.isSelected,this.buttonText,this.colorCode,this.title,this.label,this.buttonid);
}