docs: protected List<AbstractColumn> getVisibleColumns() {
  		List<AbstractColumn> visibleColums = new ArrayList<AbstractColumn>(getReport().getColumns());
  		for (DJGroup group : getReport().getColumnsGroups()) {
  			if (group.getLayout().isHideColumn()) {
  				visibleColums.remove(group.getColumnToGroupBy());
  			}
  		}
  		return visibleColums;
  	}