class Product
{
    public function __construct(
        #[SerializedName('@id')]
        public readonly int $id,
        #[SerializedName('@cat')]
        public readonly ?ProductCategory $productCategory,
    )
    {
    }
}

enum ProductCategory: string
{
    case LD = 'LD';
    case STD = 'STD';
}

// invocation
        $classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
        $metadataAwareNameConverter = new MetadataAwareNameConverter($classMetadataFactory);

        $xmlEncoder = new XmlEncoder([
            'xml_format_output' => true,
            'xml_encoding' => 'utf-8',
            'xml_version' => '1.0',
            'remove_empty_tags' => false,
        ]);

        $this->xmlEncoder = $xmlEncoder;

        $encoders = [$xmlEncoder];
        $normalizers = [
            new DateTimeNormalizer([
                DateTimeNormalizer::FORMAT_KEY => DateTimeInterface::RFC3339_EXTENDED,
                DateTimeNormalizer::TIMEZONE_KEY => null,
            ]),
            new ArrayDenormalizer(),
            new BackedEnumNormalizer(),
            new ObjectNormalizer($classMetadataFactory, $metadataAwareNameConverter, null, new PhpDocExtractor()),
        ];
        $this->serializer = new Serializer($normalizers, $encoders);