code: public FormElementController addElement(FormElementController element, int position) {
          if (element instanceof FormSectionController) {
              throw new IllegalArgumentException("Sub-sections are not supported");
          }
  
          if (elements.containsKey(element.getName())) {
              throw new IllegalArgumentException("Element with that name already exists");
          } else {
              elements.put(element.getName(), element);
              orderedElements.add(position, element);
              return element;
          }
      }
docs: Adds a form element to this section. Note that sub-sections are not supported.
  
  @param element   the form element to add
  @param position  the position at which to insert the element
  @return          the same instance of the form element that was added to support method chaining