No cascade effect if value property is undefined

[oMaten]

const data = [
  {
    label: '北京',
    value: '01',
    children: [
      {
        label: '东城区',
        value: '01-1',
      },
      {
        label: '西城区',
        value: '01-2',
      }
    ],
  },
  {
    label: '浙江',
    value: '02',
    children: [
      {
        label: '杭州',
        value: '02-1',
        children: [
          {
            label: '西湖区',
            value: '02-1-1',
          }
        ],
      },
      {
        label: '宁波',
        value: '02-2',
        children: [
          {
            label: 'xx区',
            value: '02-2-1',
          },
          {
            label: 'yy区',
            value: '02-2-2',
          },
        ],
      }
    ],
  },
];

class Demo extends React.Component<any, any> {
  render() {
    return (
        <Cascader
          data={data}
          value={undefined}
          rootNativeProps={{ 'data-xx': 'yy' }}
        />
    );
  }
}

As the example above, Cascader component has no cascade effect when value is undefined