Breaking change in ValidatorPropertyMetadataFactory: validation group callable now invoked with null

[binxiaoff]

API Platform version(s) affected: 4.1.16 and 4.1.17

Description
Hi team,

The recent PR #7184 introduced a change in the ApiPlatform\Symfony\Validator\Metadata\Property\ValidatorPropertyMetadataFactory class, where user-defined validation group callables are now invoked with a null argument.

This is a breaking change for existing projects. Previously, the callback did not need to support a nullable parameter.

There are two concerns here:

1. This change seems unnecessary. Since validation groups are meant to be dynamically determined from the input data, it’s inherently impossible to compute them meaningfully when no actual data is available.
2. It introduces unsafe behavior. Invoking user code with unexpected arguments, especially null, without an explicit contract is dangerous and error-prone.

How to reproduce

#[ApiResource(
    validationContext: [
        'groups' => [
            SomeResource::class,
            'getValidationGroups',
        ],
    ]
)]
class SomeResource
{
    // Before: worked fine
    public static function getValidationGroups(self $someResource): array
    {
        // ...
    }

    // After: now $someEntity must support null
    public static function getValidationGroups(?self $someResource): array
    {
        // ...
    }
}

Possible Solution
Please consider reverting this change.

Thanks for your work on API Platform!

[gharlan]

This can be closed, because it is fixed via #7272.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.