code: public TableCellStyle findDefaultCellStyle(final int columnIndex) {
          TableCellStyle s = this.columnStyles.get(columnIndex).getDefaultCellStyle();
          if (s == null) s = TableCellStyle.DEFAULT_CELL_STYLE;
          return s;
      }
docs: Find the default cell style for a column
  
  @param columnIndex the column index
  @return the style, null if none