docs: public int compare(Object objA, Object objB)
      {
          String idAStr = ((FieldDescriptorDef)_fields.get(objA)).getProperty("id");
          String idBStr = ((FieldDescriptorDef)_fields.get(objB)).getProperty("id");
          int    idA;
          int    idB;
  
          try
          {
              idA = Integer.parseInt(idAStr);
          }
          catch (Exception ex)
          {
              return 1;
          }
          try
          {
              idB = Integer.parseInt(idBStr);
          }
          catch (Exception ex)
          {
              return -1;
          }
          return idA < idB ? -1 : (idA > idB ? 1 : 0);
      }