Наследование: implements Sonata\Component\Product\ProductProviderInterface
 /**
  * {@inheritDoc}
  */
 public function buildEditForm(FormMapper $formMapper, $isVariation = false)
 {
     parent::buildEditForm($formMapper, $isVariation);
     $formMapper->with('Product')->add('travelDate');
     if ($isVariation) {
         $formMapper->add('travelDays')->add('travellers');
     }
     $formMapper->end();
 }