custom path to get all the subressource of an entity

I'm new with Api-platform 2.6 and i kind of succeeded to do what i attempted but i don't know if it's the "right" or easiest way to do it.

Here's what i'm trying to do:

i got an esirius_site entity that that have a collection of visitors.

The visitors are not stored in the database but they are fetched from an api endpoint.

I want to have a route like : /esirius_sites/{idsys}/visitors that return a collection of visitors (see result bellow). I don't want the route to return a esirius_site

i succeeded to do it by setting the visitors as a sub-resource:

<?php

/**
 * @ORM\Entity(repositoryClass=EsiriusSiteRepository::class)
 * @ApiResource(
 *     collectionOperations={
 *     },
 *     itemOperations={
 *              "get",
 *
 *          }
 *     )
 */
class EsiriusSite
{

    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     */
    private $idsys;

   /** Other properties... **/

    /**
     * @ApiSubresource()
     */
    private $visitors;

    public function __construct()
    {
        $this->visitors = [];
    }


    public function getIdsys(): ?int
    {
        return $this->idsys;
    }
  
    /**
     * @return array
     */
    public function getVisitors():array
    {
        return $this->visitors;
    }

    public function addVisitor(Visitor $visitor): self
    {
        $this->visitors[]=$visitor;
        $visitor->setEsiriusSite($this);
        return $this;
    }
}

and then i created a Data provider to fetch the visitor collection :

<?php

namespace App\DataProvider;

class VisitorItemDataProvider implements SubresourceDataProviderInterface,RestrictedDataProviderInterface
{
    private EsiriusVisitorWebService $visitorWebService;
    private EsiriusSiteRepository $siteRepository;

    public function __construct(EsiriusVisitorWebService $visitorWebService, EsiriusSiteRepository $siteRepository)
    {
        $this->visitorWebService = $visitorWebService;
        $this->siteRepository = $siteRepository;
    }

    public function supports(string $resourceClass, string $operationName = null, array $context = []): bool
    {
        return $resourceClass === Visitor::class;
    }


    public function getSubresource(string $resourceClass, array $identifiers, array $context, string $operationName = null)
    {
        $site = $this->siteRepository->find($identifiers["idsys"]["idsys"]);
        $esiriusVisitors = ($this->visitorWebService->getVisitors([$site->getCode()]))->visitorArray;
        if($esiriusVisitors== new \stdClass())
            return [];

        foreach ($esiriusVisitors as $visitor) {
            $newVisitor = (new Visitor())->setFirstName($visitor->firstName)->setLastname($visitor->name)->setId($visitor->businessIdentity);
            $site->addVisitor($newVisitor);
        }
        return $site->getVisitors();
    }
}

In this data provider i use the SubresourceDataProviderInterface (i found it randomly) that's not mentioned in the api platform documentation.

I finally got the result that i espect:

{
    "@context": "/q0met-api/contexts/Visitor",
    "@id": "/q0met-api/esirius_sites/18/visitors",
    "@type": "hydra:Collection",
    "hydra:member": [
        {
            "@id": "/q0met-api/visitors/1234",
            "@type": "Visitor",
            "id": "1234",
            "firstName": "Jean",
            "lastname": "Michel",
            "esiriusSite": "/q0met-api/esirius_sites/18"
        }
    ],
    "hydra:totalItems": 1
}