code: public WizardPage addForm(Form formPage) {
          Assert.notNull(formPage, "The form page cannot be null");
          WizardPage page = new FormBackedWizardPage(formPage, !autoConfigureChildPages);
          addPage(page);
          return page;
      }
docs: Adds a new page to this wizard. The page is created by wrapping the form in a
  {@link FormBackedWizardPage} and appending it to the end of the page list.
  
  @param formPage The form page to be added to the wizard.
  @return the newly created wizard page that wraps the given form.
  
  @throws IllegalArgumentException if {@code formPage} is null.