title: Symfony Form Component - change a field with addEventListener PRE_SUBMIT
body: <p>I have custom Form Type:</p>
  <pre><code>class ChoosyType extends AbstractType
  {
  
      private EntityManagerInterface $entityManager;
  
  
      public function __construct(EntityManagerInterface $entityManager)
      {
          $this-&gt;entityManager = $entityManager;
      }
  
  
      public function buildForm(FormBuilderInterface $builder, array $options)
      {
  
          $builder-&gt;addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event) use ($options) {
              $form = $event-&gt;getForm();
              $parentForm = $form-&gt;getParent();
              $data = $event-&gt;getData();
  
              $newChoices = $this-&gt;createNewChoices($options['choices']);
  
              $parentForm-&gt;add($form-&gt;getName(), ChoosyType::class, array_replace($options, [
                  'choices' =&gt; $newChoices,
                  'data' =&gt; $this-&gt;entityManager-&gt;getRepository($options['class'])-&gt;find($data)
              ]));
          });
      }
  </code></pre>
  <p>When I submit my form - the change does not happen.
  This is resulting only when I add the field to the parent form.
  If I do not do this all works fine with the given choices.</p>
  <p>Means when I add the new field - the value gets lost.</p>
  <p>Did I something wrong or is this a know limitiation?</p>