Dynamic/Types/FreeTextType.php
public function build(FormBuilderInterface $builder, FormField $field, $locale, $options = [])
    {
        $options['mapped'] = false;
        $options['attr']['type'] = $field->getType();

        $type = HiddenType::class;
        $builder->add($field->getKey(), $type, $options);
    }
public function build(FormBuilderInterface $builder, FormField $field, $locale, $options = [])
    {
        $options['mapped'] = false;
        $options['attr']['type'] = $field->getType();

        $type = HiddenType::class;
        $builder->add($field->getKey(), $type, $options);
    }
{@inheritdoc}