private void clampPositionToTopStackEnd(StackScrollState.ViewState childViewState,int childHeight){
  childViewState.yTranslation=Math.max(childViewState.yTranslation,mCollapsedSize - childHeight);
}

private void clampPositionToTopStackEnd ( StackScrollState . ViewState childViewState , int childHeight ) { childViewState . yTranslation = Math . max ( childViewState . yTranslation , mCollapsedSize - childHeight ) ; }
clamp the ytranslation of the child up such that its end is at lest on the end of the top stack . get
