      TableCellBuilder th = out.startTH().className(classesBuilder.toString());

      // Associate the cell with the column to enable sorting of the column.
      enableColumnHandlers(th, column);

      // Render the header.
      Context context = new Context(0, 2, header.getKey());
      renderSortableHeader(th, context, header, isSorted, isSortAscending);

      // End the table cell.
      th.endTH();
    }
  }

  /**
   * Renders custom table footers that appear beneath the columns in the table.
   *