code: @SuppressWarnings("unused")
      private void setDraggingToColumn(int column, boolean isDragging) {
          Collection<ViewHolder> holders = mViewHolders.getColumnItems(column);
          for (ViewHolder holder : holders) {
              holder.setIsDragging(isDragging);
          }
  
          ViewHolder holder = mHeaderColumnViewHolders.get(column);
          if (holder != null) {
              holder.setIsDragging(isDragging);
          }
      }
docs: Method set dragging flag to all view holders in the specific column
  
  @param column     specific column
  @param isDragging flag to set