Get serialization context groups in controller - symfony

Question

I have the problem that depending on user rights, there are different context groups used, and I can't find the place where the context groups are set.
For debugging issues I'm searching an possibility to find out which serialization context group an api call is using. This is my code:
<?php
namespace AppBundle\Controller\Api\Upload;
use AppBundle\Entity\Upload\UploadRepository;
use AppBundle\Entity\Upload\UploadType;
use AppBundle\Entity\Upload\UploadTypeRepository;
use Doctrine\ORM\ORMException;
use GuzzleHttp\Psr7\UploadedFile;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Nelmio\ApiDocBundle\Annotation\ApiDoc;
use ApiPlatform\Core\Annotation\ApiResource;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Annotation\Route;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
use AppBundle\General\Registry;
use Symfony\Component\Security\Core\Exception\BadCredentialsException;
use Symfony\Component\Serializer\Normalizer\DataUriNormalizer;
use AppBundle\Entity\Upload\Upload;
use AppBundle\Entity\Application\ApplicationData;
use Symfony\Component\HttpFoundation\BinaryFileResponse;
use Symfony\Component\Serializer\Serializer;
/**
* Class UploadController
*
* #package AppBundle\Controller\Api\Upload
*
* #ApiDoc()
* #ApiResource(attributes={"pagination_enabled"=true})
*/
class UploadController extends Controller
/**
* Get an upload.
*
* #ApiDoc(
* resource=true,
* description="gets an upload",
* )
* #Route(
* name="getUploadSpecial",
* path="/fileuploads/{id}",
* defaults={"_api_resource_class"=Upload::class, "_api_item_operation_name"="getUpload"}
* )
* #Method("GET")
*
* #param Upload $data
*
* #return null|string
*
*/
public function getUploadAction($data)
{
// here I'd like to return the serialization context group
return $data;
}
Is there the possibility to get the serialization context group in the controller?

Answer 1

Well, it seems, the controller isn't the right place to find it.
It is better to dump in
src/Serializer/JsonEncoder.php in function encode, right before the return like this:
/**
* {#inheritdoc}
*/
public function encode($data, $format, array $context = [])
{
dump($data, $context);die;
return $this->jsonEncoder->encode($data, $format, $context);
}