Embedded Form shenanigans

stuff.php

<?php
// in the controller
$user->addCreditCard(new CreditCard());
// this actually shows up in the form.
$user->getCreditCards()[0]->setCvv(123);

// in the outer form type
$builder->add(
    'credit_card',
    CollectionType::class,
    [
        'type' => CreditCardType::class,
        'property_path' => 'creditCards',
        'entry_options' => [
            //'validation_groups' => ['credit_card'],
            'container' => $container,
            // this is just me being desperate
            'constraints' => [new Assert\Valid(), new Assert\NotBlank()],
        ],
    ]
)

// Inner form type 
// This is extra, just to test if the failure happens at entity level. But this check is ignored.
$builder->add('number', TextType::class, ['constraints' => [new Assert\NotBlank()]]);