code: public List<String> getFilterPickList(final UITableHeader _uitableHeader)
          throws EFapsException
      {
          final List<String> ret = new ArrayList<>();
          for (final UIRow rowmodel : this.values) {
              for (final IFilterable cell : rowmodel.getCells()) {
                  if (cell.belongsTo(_uitableHeader.getFieldId())) {
                      final String value = cell.getPickListValue();
                      if (!ret.contains(value)) {
                          ret.add(value);
                      }
                      break;
                  }
              }
          }
          Collections.sort(ret);
          return ret;
      }
docs: Get the List of values for a PICKERLIST.
  
  @param _uitableHeader UitableHeader this filter belongs to
  @return List of Values
  @throws EFapsException on error