code: public FormField getHiddenFormTypeField() {
          FormField field = getField(FormField.FORM_TYPE);
          if (field != null && field.getType() == FormField.Type.hidden) {
              return field;
          }
          return null;
      }
docs: Returns the hidden FORM_TYPE field or null if this data form has none.
  
  @return the hidden FORM_TYPE field or null.
  @since 4.1