Denormalizer on MongoDb Embedded Document in Symfony API Platform

I am attempting to run a denormalizer (data in) on an embedded mongodb document with Symfony 4.4 using the Api Platform bundle. This works as expected for normalization (data out), but for the denormalization process nothing is fired on the embedded data, just on the parent data.

If this is the way it works, then I may need to move the logic for denormalization into the parent. Or perhaps I am just doing something wrong. What I am attempting to accomplish is throw exceptions on inbound requests that contain fields which have been deprecated. The classes which parse the annotations and scan the attributes works as expected, its just determining where to plug it in and I was hoping the denormalization process on embedded documents would work.

Here is my services.yaml:

'App\Serializer\InvestmentNormalizer':
    arguments: [ '@security.authorization_checker' ]
    tags:
        - { name: 'serializer.normalizer', priority: 64 }
'App\Serializer\InvestmentDenormalizer':
    tags:
        - { name: 'serializer.denormalizer', priority: 64 }
'App\Serializer\ProjectNormalizer':
    tags:
        - { name: 'serializer.normalizer', priority: 64 }
'App\Serializer\ProjectDenormalizer':
    tags:
        - { name: 'serializer.denormalizer', priority: 64 }

Then my denormalizer class which never gets executed:

class ProjectDenormalizer implements DenormalizerInterface
{
    private const ALREADY_CALLED = 'PROJECT_DENORMALIZER_ALREADY_CALLED';

    public function denormalize($data, $class, $format = null, array $context = [])
    {
        $context[self::ALREADY_CALLED] = true;

        return $this->removeDeprecatedFields($data);
    }

    public function supportsDenormalization($data, $type, $format = null)
    {
        if (isset($context[self::ALREADY_CALLED])) {
            return false;
        }

        return $type == get_class(new Project());
    }

    private function removeDeprecatedFields(array $normalizedData) : array
    {
        $apiPropertyReader = new AnnotationReader(Project::class, ApiProperty::class);
        $deprecatedProperties = $apiPropertyReader->readAllHavingAttribute('deprecationReason');

        $errors = [];

        foreach (array_keys($deprecatedProperties) as $deprecatedPropertyName) {

            if (!isset($normalizedData[$deprecatedPropertyName])) {
                continue;
            }

            $errors[] = $deprecatedPropertyName . ' has been deprecated';
        }

        if (!empty($errors)) {
            throw new DeprecatedFieldException(implode('. ', $errors));
        }

        return $normalizedData;
    }
}