code: public static List<Column> getColumnList(List<ColumnOrSuperColumn> columns) {
      ArrayList<Column> list = new ArrayList<Column>(columns.size());
      for (ColumnOrSuperColumn col : columns) {
        list.add(col.getColumn());
      }
      return list;
    }
docs: Converts a list of ColumnOrSuperColumn to Column
  @param columns
  @return