findSnapView
Override this method to provide a particular target view for snapping.
This method is called when the SnapHelper is ready to start snapping and requires a target view to snap to. It will be explicitly called when the scroll state becomes idle after a scroll. It will also be called when the SnapHelper is preparing to snap after a fling and requires a reference view from the current set of child views.
If this method returns null, SnapHelper will not snap to any view.
Return
the target view to which to snap on fling or end of scroll
Parameters
layoutManager
the RecyclerView.LayoutManager associated with the attached RecyclerView