DTO as resource - auto convert subresource identifiers to objects

Hi,

I've created subresource. This resource is DTO, not an entity.

```php
#[ApiResource(
operations: [
new Post(
uriTemplate: '/events/{eventId}/participants/{participantId}/images.{_format}',
uriVariables: [
# possible bug below
'eventId' => new Link(fromClass: EventResource::class, toProperty: 'event'),
'participantId' => new Link(fromClass: EventParticipantResource::class, toProperty: 'participant'),
],
processor: CreateEventParticipantImageProcessor::class,
),
/** ... */
readonly class EventParticipantImageResource
```

Problem is that in `CreateEventParticipantImageProcessor` I can use only uri variables cause query is not serialized:
```php
public function process(mixed $data, Operation $operation, array $uriVariables = [], array $context = []) {
$eventId = $uriVariables['eventId']; # identifier
$eventId = $data->event?->id; # null
}
```

Is there functionality that will convert identifiers to target resources and assign to DTO fields so I can use `$data->event?->id`?