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

    public function getDate()
    {
        if (!$this->headers->has('Date')) {
            $this->setDate(\DateTime::createFromFormat('U', time()));
        }

        return $this->headers->getDate('Date');
    }

 /**
  * {@inheritdoc}
  */
 public function getDate()
 {
     $date = $this->headers->getDate('Date', null);
     if ($date === null) {
         $this->setDate(new \DateTime('now'));
     }
     return parent::getDate();
 }