Symfony\Component\HttpFoundation\Response::setDate PHP Method

    public function setDate(\DateTime $date)
    {
        $date->setTimezone(new \DateTimeZone('UTC'));
        $this->headers->set('Date', $date->format('D, d M Y H:i:s').' GMT');

        return $this;
    }

 /**
  * Sends HTTP headers.
  *
  * @param ReactResponse   $response
  * @param SymfonyResponse $sf_response
  */
 private function sendHeaders(ReactResponse $response, SymfonyResponse $sf_response)
 {
     // date
     if (!$sf_response->headers->has('Date')) {
         $sf_response->setDate(\DateTime::createFromFormat('U', time()));
     }
     $headers = $sf_response->headers->allPreserveCase();
     // cookies
     foreach ($sf_response->headers->getCookies() as $cookie) {
         if (!isset($headers['Set-Cookie'])) {
             $headers['Set-Cookie'] = [];
         }
         $headers['Set-Cookie'][] = (string) $cookie;
     }
     $response->writeHead($sf_response->getStatusCode(), $headers);
 }