ListCredential.php

<?php

namespace App\Credential;

use Utreino\Core\Domain\Repository\RepositoryInterface;
use Utreino\Core\Infrastructure\Proxy\RepositoryPaginatorProxy;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Zend\Diactoros\Response\JsonResponse;

class ListCredential
{

    private $repository;

    public function __construct(RepositoryInterface $repository)
    {
        $this->repository = $repository;
    }

    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next = null)
    {
        $params = $request->getQueryParams();

        $limit = isset($params['limit']) && is_numeric($params['limit']) ? $params['limit'] : 10;
        $offset = isset($params['offset']) && is_numeric($params['offset']) ? $params['offset'] : 0;

        $uuid = $request->getAttribute('uuid');

        if ( ! is_null($uuid)) {

            $credential = $this->repository->findByUuid($uuid);

            if( is_null($credential) )
                $response = new JsonResponse(null, 404, ['Message' => 'Credential not exists']);
            else
                $response = new JsonResponse($credential->toArray(), 200, ['Message' =>  'Credential exists']);

        } else {

            $credentials = (new RepositoryPaginatorProxy($this->repository))
                ->findPaginatorByToArray([], [], $limit, $offset);

            $response =  new JsonResponse($credentials, 200, ['Message' => 'List credential']);
        }

        if ($next)
            $next($request, $response, $next);

        return $response;
    }
}

Rota: api/v1/credentials
Response:
HTTP/1.1 200 OK
Date: Mon, 07 Nov 2016 17:35:18 GMT
Server: Apache/2.4.10 (Debian)
X-Powered-By: PHP/5.6.26
Message: List credential
Content-Length: 1982
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: application/json