code: public DynaFormModelElement addModel(final DynaFormModel model, final int colspan, final int rowspan) {
          final DynaFormModelElement nestedModel = new DynaFormModelElement(model,
                      colspan,
                      rowspan,
                      row,
                      elements.size() + 1,
                      dynaFormModel.getControls().size() + 1,
                      extended);
  
          elements.add(nestedModel);
          dynaFormModel.getControls().addAll(model.getControls());
          totalColspan = totalColspan + colspan;
  
          return nestedModel;
      }
docs: *
  Adds nested model with given colspan and rowspan.
  
  @param model
  @param colspan
  @param rowspan
  @return DynaFormModelElement added model