Zend PSR7 response does not seem to work?

Zend PSR7 response does not seem to work on Lumen:

use Psr\Http\Message\ServerRequestInterface;
use Zend\Diactoros\Response;

// PSR 7
$app->bind('Psr\Http\Message\ServerRequestInterface', function ($app) {
    return (new Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory)->createRequest($app->make('request'));
});

// PSR 7.
$app->get('hello/{name}', function (ServerRequestInterface $request, $name) {

    // Interact with the PSR-7 response
    $response = new Response();
    $response->getBody()->write('Hello, ' . $name);

    return $response->withHeader('Content-type', 'application/json');
});

ERROR:

UnexpectedValueException in Response.php line 395:
The Response content must be a string or object implementing __toString(), "object" given.
in Response.php line 395
at Response->setContent(object(Response)) in Response.php line 54
at Response->setContent(object(Response)) in Response.php line 198
at Response->__construct(object(Response)) in Application.php line 1454
at Application->prepareResponse(object(Response)) in Application.php line 1314
at Application->callActionOnArrayBasedRoute(array('1', array(object(Closure)), array('name' => 'world'))) in Application.php line 1288
at Application->handleFoundRoute(array('1', array(object(Closure)), array('name' => 'world'))) in Application.php line 1262
at Application->handleDispatcherResponse(array('1', array(object(Closure)), array('name' => 'world'))) in Application.php line 1212
at Application->Laravel\Lumen\{closure}() in Application.php line 1442
at Application->sendThroughPipeline(array(), object(Closure)) in Application.php line 1213
at Application->dispatch(object(Request)) in Application.php line 1153
at Application->run(object(Request)) in index.php line 28

Any ideas why?