code: @Override
    public void add(Entity entity) {
      if (entity == null) throw new IllegalArgumentException("Entity cannot be null");
      if (cachedAttributes == null)
        throw new MolgenisDataException(
            "The attribute names are not defined, call writeAttributeNames first");
  
      int i = 0;
      Row poiRow = sheet.createRow(row++);
      for (Attribute attribute : cachedAttributes) {
        Cell cell = poiRow.createCell(i++, CellType.STRING);
        cell.setCellValue(toValue(entity.get(attribute.getName())));
      }
  
      entity.getIdValue();
    }
docs: Add a new row to the sheet