streams.php

function toJsonResponse(ApiProblem $problem, ResponseInterface $response)
{
    $body = $response->getBody();
    $body->rewind();
    $body->write($problem->asJson($this->pretty));


    return $this->toResponse($problem, $response)
        ->withHeader('Content-Type', 'application/problem+json')
        ->withBody($body);
}