HarmonyOS List 组件头部插入数据的默认行为不符合预期

参考以下代码

import LazyDataSource from "./LazyDataSource"
@Entry
@Component
struct ListExample {
  @State arr: LazyDataSource<number> = new LazyDataSource()
  @State start: number = 0
  private scrollerForList: Scroller = new Scroller()

  aboutToAppear(): void {
    this.arr.pushArrayData([0,1,2,3,4,5,6,7,8,9])
  }
  loadData(){

  }
  build() {
    Column() {
      List({ space: 20, initialIndex: 0 ,scroller: this.scrollerForList}) {
        LazyForEach(this.arr, (item: number,index:number) => {
          ListItem() {
            Text('' + item)
              .width('100%').height(index%2?100:50).fontSize(16)
              .textAlign(TextAlign.Center).borderRadius(10).backgroundColor(0xFFFFFF)
          }
        }, (item: string) => item + Math.random())
      }
      .listDirection(Axis.Vertical) // 排列方向
      .scrollBar(BarState.Off)
      .friction(0.6)
      .divider({ strokeWidth: 2, color: 0xFFFFFF, startMargin: 20, endMargin: 20 }) // 每行之间的分界线
      .edgeEffect(EdgeEffect.Spring) // 边缘效果设置为Spring
      .onScrollIndex((firstIndex: number, lastIndex: number, centerIndex: number) => {
        this.start = firstIndex
        console.info('first' + firstIndex)
        console.info('last' + lastIndex)
        console.info('center' + centerIndex)
      })
      .onScrollVisibleContentChange((start: VisibleListContentInfo, end: VisibleListContentInfo) => {
        console.log(' start index: ' + start.index +
          ' start item group area: ' + start.itemGroupArea +
          ' start index in group: ' + start.itemIndexInGroup)
        console.log(' end index: ' + end.index +
          ' end item group area: ' + end.itemGroupArea +
          ' end index in group: ' + end.itemIndexInGroup)
      })
      .onDidScroll((scrollOffset: number, scrollState: ScrollState) => {
        console.info(`onScroll scrollState = ScrollState` + scrollState + `, scrollOffset = ` + scrollOffset)
      })
      .width('90%')
      .height("70%")

      Button() { Text('在顶部添加') }.onClick(()=>{
        let indexOffset = this.scrollerForList.getItemRect(this.start).y
        this.arr.addData(0,-1)
        this.arr.addData(0,-2)
        this.arr.addData(0,-3)
        this.scrollerForList.scrollToIndex(this.start + 3)//添加的个数
        this.scrollerForList.scrollBy(0, -indexOffset);

      }).height(50).width('30%')
      Button() { Text('在底部添加') }.onClick(()=>{
        // this.arr.pushData(-1)
        this.arr.appendArrayData([-1,-2,-3])
      }).height(50).width('30%')
    }
    .width('100%')
    .height('100%')
    .backgroundColor(0xDCDCDC)
    .padding({ top: 5 })
  }
}