$serializer = new Serializer(array(new DateTimeNormalizer(array('datetime_format' => 'd.m.Y')), new GetSetMethodNormalizer()), array('json' => new JsonEncoder()));

$encoder = new JsonEncoder();
    $normalizer = new ObjectNormalizer();

    $normalizer->setCircularReferenceHandler(function ($object, string $format = null, array $context = []) {
        return $object->getName();
    });

    $serializer = new Serializer([$normalizer], [$encoder]);

$encoder = new JsonEncoder();
    $normalizer = new ObjectNormalizer();

    $normalizer->setCircularReferenceHandler(function ($object, string $format = null, array $context = []) {
        return $object->getName();
    });

    $serializer = new Serializer([$normalizer], [$encoder], array(new DateTimeNormalizer(array('datetime_format' => 'd.m.Y')), new GetSetMethodNormalizer()), array('json' => new JsonEncoder()));

$serializer = new Serializer(new DateTimeNormalizer(array('datetime_format' => 'd.m.Y')),[$normalizer], [$encoder]);

$encoder = new JsonEncoder();
    $normalizer = new ObjectNormalizer();
    $dateNormalizer = new DateTimeNormalizer(array('datetime_format' => 'd.m.Y'));

    $normalizer->setCircularReferenceHandler(function ($object, string $format = null, array $context = []) {
        return $object->getName();
    });

    $serializer = new Serializer([$dateNormalizer], [$normalizer], [$encoder]);