Serializing an object tree fails

Questions Mezzio
1

I’m having some difficulty serializing what I call an object tree. I’m using mezzio-hal (v3) with the following HAL config:

[
    '__class__' => RouteBasedResourceMetadata::class,
    'resource_class' => Handler\PersonEntity::class,
    'route' => 'list.persons',
    'extractor' => ClassMethodsHydrator::class,
],
[
    '__class__' => RouteBasedCollectionMetadata::class,
    'collection_class' => Handler\PersonCollection::class,
    'collection_relation' => 'persons',
    'route' => 'list.persons',
],

This is my collection class:

class PersonCollection extends Paginator
{
}

This is my entity class:

class PersonEntity
{
    private $id;
    private $name;

    public function getId() : int
    {
        return $this->id;
    }

    public function setId(int $id) : self
    {
        $this->id = $id;
        return $this;
    }

    public function getName() : NameEntity
    {
        if (null === $this->name) {
            $this->name = new NameEntity();
            $this->name->setFirstName('fn');
            $this->name->setLastName('ln');
        }
        return $this->name;
    }

    public function setName(NameEntity $name) : self
    {
        $this->name = $name;
        return $this;
    }
}

class NameEntity
{
    private $firstName;
    private $lastName;

    public function getFirstName() : string
    {
        return $this->firstName;
    }

    public function setFirstName(string $firstName) : self
    {
        $this->firstName = $firstName;
        return $this;
    }

    public function getLastName() : string
    {
        return $this->lastName;
    }

    public function setLastName(string $lastName) : self
    {
        $this->lastName = $lastName;
        return $this;
    }
}

This is my HAL building command:

$halResource = $this->getResourceGenerator()->fromObject($personCollection, $request);

And at least this is my output:

{
    "_total_items": 1,
    "_page": 1,
    "_page_count": 1,
    "_links": {
        "self": {
            "href": "/api/persons?page=1"
        }
    },
    "_embedded": {
        "persons": [
            {
                "id": 1,
                "name": {},
                "_links": {
                    "self": {
                        "href": "/api/persons/1"
                    }
                }
            }
        ]
    }
}

What I want to know: Why is the name attribute empty? Why is the NameEntity not output correctly? Is this a bug?