code: @Override
      public void unBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {
          IItem item = FastAdapter.getHolderAdapterItemTag(viewHolder);
          if (item != null) {
              item.unbindView(viewHolder);
              if (viewHolder instanceof FastAdapter.ViewHolder) {
                  ((FastAdapter.ViewHolder) viewHolder).unbindView(item);
              }
              //remove set tag's
              viewHolder.itemView.setTag(R.id.fastadapter_item, null);
              viewHolder.itemView.setTag(R.id.fastadapter_item_adapter, null);
          } else {
              Log.e("FastAdapter", "The bindView method of this item should set the `Tag` on its itemView (https://github.com/mikepenz/FastAdapter/blob/develop/library-core/src/main/java/com/mikepenz/fastadapter/items/AbstractItem.java#L189)");
          }
      }
docs: is called in onViewRecycled to unbind the data on the ViewHolder
  
  @param viewHolder the viewHolder for the type at this position
  @param position   the position of this viewHolder