docs: @Override
    public XSSFRichTextString getRichStringCellValue() {
      CellType cellType = getCellType();
      XSSFRichTextString rt;
      switch (cellType) {
        case BLANK:
          rt = new XSSFRichTextString("");
          break;
        case STRING:
          rt = new XSSFRichTextString(getStringCellValue());
          break;
        default:
          throw new NotSupportedException();
      }
      return rt;
    }