View is not focused

So the situation is:
`CoordinatorLayout > AppBarLayout > Toolbar(1 child) + ConstraintLayout(2 child)` is OK, works as intended
`CoordinatorLayout > AppBarLayout > Toolbar(1 child) + ConstraintLayout(2 child) > any child of ConstraintLayout` is BAD, blurs and not highlighted

Start by reproducing the issue in the BlurTutorial Android project using the two view hierarchies described in the report, comparing focus and highlighting behavior. Trace the relevant view and blur setup entry points; done means a child of the ConstraintLayout remains focused and highlighted without the reported blur.

索引モデルが issue の本文から書いたものです。