code: private List<Element> getClassElements(final UIClassification _uiclass,
                                             final Map<UUID, String> _uuid2InstanceKey)
          throws EFapsException
      {
          final List<Element> ret = new ArrayList<>();
          if (_uiclass.isSelected() && !_uiclass.isRoot()) {
              final UIFieldForm fieldform;
              if (_uuid2InstanceKey.containsKey(_uiclass.getClassificationUUID())) {
                  fieldform = new UIFieldForm(getCommandUUID(),
                                  _uuid2InstanceKey.get(_uiclass.getClassificationUUID()));
              } else {
                  fieldform = new UIFieldForm(getCommandUUID(), _uiclass);
                  if (isEditMode()) {
                      // in edit mode, if there is no classification yet, create
                      // mode must be forced
                      fieldform.setMode(TargetMode.CREATE);
                  }
              }
              ret.add(new Element(ElementType.SUBFORM, fieldform));
          }
          for (final UIClassification child : _uiclass.getChildren()) {
              ret.addAll(getClassElements(child, _uuid2InstanceKey));
          }
          Collections.sort(ret, (_o1,
           _o2) -> ((UIFieldForm) _o1.getElement()).getWeight().compareTo(
                          ((UIFieldForm) _o2.getElement()).getWeight()));
          return ret;
      }
docs: Recursive method to add the children classification forms.
  
  @param _uiclass parent classification form
  @param _uuid2InstanceKey mapping of instancekeys
  @return List of elements to be added
  @throws EFapsException on error