inlining children of a self-referencing to an IRI in API Platform

CheeseNormalizer.php

<?php

namespace App\Serializer\Normalizer;

use App\Entity\CheeseListing;
use Symfony\Component\Serializer\Normalizer\CacheableSupportsMethodInterface;
use Symfony\Component\Serializer\Normalizer\ContextAwareNormalizerInterface;
use Symfony\Component\Serializer\Normalizer\NormalizerAwareInterface;
use Symfony\Component\Serializer\Normalizer\NormalizerAwareTrait;

class CheeseNormalizer implements ContextAwareNormalizerInterface, CacheableSupportsMethodInterface, NormalizerAwareInterface
{
    use NormalizerAwareTrait;

    private const ALREADY_CALLED = 'USER_NORMALIZER_ALREADY_CALLED';

    public function normalize($object, $format = null, array $context = array())
    {
        $context[self::ALREADY_CALLED] = true;

        // set the groups to nothing so that no data is serialized from
        // the child object
        $context['groups'] = [];
        // not sure why this is needed. This is normally added
        // by the JSON-LD ObjectNormalizer, but that doesn't seem to
        // be used... and the logic here is quite hard to follow.
        // so, I added it myself - it's the flag that converting to an
        // IRI is ok
        $context['api_empty_resource_as_iri'] = true;
        $data = $this->normalizer->normalize($object, $format, $context);

        $context[self::ALREADY_CALLED] = false;

        return $data;
    }

    public function supportsNormalization($data, $format = null, array $context = [])
    {
        // avoid recursion: only call once per object
        if (isset($context[self::ALREADY_CALLED])) {
            return false;
        }

        // api_attribute is a context key set to the property being normalized
        return $data instanceof CheeseListing
            && isset($context['api_attribute'])
            && in_array($context['api_attribute'], ['parentCheese', 'childCheeses']);
    }

    public function hasCacheableSupportsMethod(): bool
    {
        return false;
    }
}

Here's a different solution a user posted - https://gist.github.com/voltel/ac2820fc7f97892999162774452a97fa

Reference: https://symfonycasts.com/screencast/api-platform/relations-iri#comment-5391015233

Thanks to @voltel :)