parent controller's onAttach called when using SharedElementElement.

Hello. I have a question.
Here is my change handler.
```
class SharedElementChangeHandler : TransitionChangeHandler() {
override fun getTransition(container: ViewGroup, from: View?, to: View?, isPush: Boolean): Transition {
return TransitionSet().apply {
ordering = TransitionSet.ORDERING_SEQUENTIAL
addTransition(Fade(Fade.OUT))
addTransition(TransitionSet().apply {
addTransition(ChangeBounds())
addTransition(ChangeClipBounds())
addTransition(ChangeTransform())
})
}
}
}
```

And use that,
```
AController {
router.pushController(RouterTransaction.with(BController())
.pushChangeHandler(SharedElementChangeHandler())
.popChangeHandler(SharedElementChangeHandler()))
```
then `AController.onAttach` called after `BController.onAttach`.

Is it a bug or is it intended?

Start with the controller lifecycle entry points mentioned in the report, especially AController.onAttach, BController.onAttach, and the SharedElementChangeHandler transition. Reproduce the push using the shown RouterTransaction and determine whether the observed attachment order is intended. Done means the issue has a documented lifecycle expectation and, if it is a bug, a verified correction.

Written by the indexing model from the issue text.