HarmonyOS @Observed/@ObjectLink装饰器可以观察三层四层的嵌套么，第三层数据修改但视图不更新

testA1不更新，testA2正常，代码如下：

@Observed
export class B {
  testB = 0
  testA: A = new A()
}
@Observed
export class A {
  a = 0
}
@Entry
@Component
struct ObservedQ1 {
  @State itemB: B = new B()
  build() {
    Column() {
      Column() {
        TestB({
          itemB: this.itemB,
          itemA: this.itemB.testA
        })
          .margin({ bottom: 20 })
        Button("this.itemB.testA.a++")
          .onClick(() => {
            this.itemB.testA.a += 1
          })
      }.width('100%')
      .backgroundColor('#33ff0000')
    }
  }
}
@Component
struct TestB {
  @ObjectLink itemB: B
  @ObjectLink itemA: A
  build() {
    Column() {
      Text(`testA1 : ${this.itemB.testA.a}`)
      Text(`testA2 : ${this.itemA.a}`)
    }
  }
}