class MyObject
{
  #[SerializedName('entry')]
  public $list = [];
  #[SerializedPath("[outer][inner]")]
  public $outer = [];
}

class MyObject
{
  #[SerializedName('entry')]
  public $list = [];
  #[SerializedPath("[outer][inner]")]
  public $outer = [];
}


$loaderChain = new LoaderChain([
    new AttributeLoader(),
]);
$classMetadataFactory = new ClassMetadataFactory($loaderChain);
$nameConverter = new MetadataAwareNameConverter($classMetadataFactory);

$phpDocExtractor = new PhpDocExtractor();
$reflectionExtractor = new ReflectionExtractor();
$typeExtractor   = new PropertyInfoExtractor(
    typeExtractors: [ new ConstructorExtractor([$phpDocExtractor]), $phpDocExtractor, $reflectionExtractor]
);

$serializer = new Serializer(
    normalizers: [
        new ArrayDenormalizer(),
        new ObjectNormalizer($classMetadataFactory, $nameConverter, null, $typeExtractor),
                 ],
    encoders:    ['xml' => new XmlEncoder()]
);


$object = new MyObject();

try {
    var_dump(
        $serializer->normalize($object, 'xml')
    );

    var_dump($serializer->serialize($object, 'xml', [
        XmlEncoder::FORMAT_OUTPUT => true
    ]));
} catch (Throwable $t) {
    var_dump($t);
}