code: public DynaFormRow createExtendedRow() {
          if (extendedRows == null) {
              extendedRows = new ArrayList<DynaFormRow>();
          }
  
          final DynaFormRow dynaFormRow = new DynaFormRow(extendedRows.size() + 1, true, this);
          extendedRows.add(dynaFormRow);
  
          return dynaFormRow;
      }
docs: Creates a new extended row.
  
  @return {@link DynaFormRow}