/**
  * Register a RecyclerView to the current MaterialViewPagerAnimator Listen to
  * RecyclerView.OnScrollListener so give to $[onScrollListener] your RecyclerView.OnScrollListener
  * if you already use one For loadmore or anything else
  *
  * @param activity current context
  * @param recyclerView the scrollable
  * @param onScrollListener use it if you want to get a callback of the RecyclerView
  */
 public static void registerRecyclerView(
     Activity activity,
     RecyclerView recyclerView,
     RecyclerView.OnScrollListener onScrollListener) {
   if (activity != null && hashMap.containsKey(activity)) {
     MaterialViewPagerAnimator animator = hashMap.get(activity);
     if (animator != null) {
       animator.registerRecyclerView(recyclerView, onScrollListener);
     }
   }
 }