Collapsing Constraint Layout
This is based on the DroidCon SF video https://www.youtube.com/watch?v=8lAXJ5NFXTM (21 mins) and was created to answer https://stackoverflow.com/questions/51018405/collapsing-toolbar-layout-using-constraintlayout
The idea is to use ConstraintLayout with two ConstraintSets over Collapsing toolbar.
This will give you a lot more flexibility in the animations you create as the toolbar collapses.