code: public void addColumn(Column<T, ?> column, Header<?> header,
                            boolean sortable) {
          addColumn(column, header);
          column.setSortable(sortable);
          if (sortable) {
              defaultSortOrderMap.put(column, true);
          }
      }
docs: Adds a column to the table and sets its sortable state
  
  @param column
  @param header
  @param sortable