code: public TableCellStyle addChildCellStyle(final TableCellStyle style, final TableCell.Type type) {
          final TableCellStyle newStyle;
          final DataStyle dataStyle = this.format.getDataStyle(type);
          if (dataStyle == null) {
              newStyle = style;
          } else {
              newStyle = this.stylesContainer.addChildCellStyle(style, dataStyle);
          }
          return newStyle;
      }
docs: Create an automatic style for this TableCellStyle and this type of cell.
  Do not produce any effect if the type is Type.STRING or Type.VOID.
  
  @param style the style of the cell (color, data style, etc.)
  @param type  the type of the cell
  @return the created style, or style if the type is Type.STRING or Type.VOID