Как валидировать внутренний массив в Symfony 4, который содержит объекты?

$constraint = new Assert\Collection(
    [
        'fields' => [
            'cf_sub_products' => [
                new Assert\NotBlank(),
                new Assert\Type('array'),
                new Assert\All([
                    new Assert\Collection([
                        'fields' => [
                            "size" => [
                                new Assert\NotBlank(),
                            ],
                            "cf_product_id" => [
                                new Assert\NotBlank(),
                            ],
                            "enabled" => [
                                new Assert\NotBlank(),
                            ],
                            "price" => [
                                new Assert\NotBlank(),
                            ],
                            "sku" => [
                                new Assert\NotBlank(),
                            ],
                        ],
                    ])
                ])
            ]
        ]
    ]
);
$violations = $validator->validate($body, $constraint);