Contao\CoreBundle\EventListener\UserSessionListener::onKernelResponse PHP Method

    public function onKernelResponse(FilterResponseEvent $event)
    {
        if (!$this->isContaoMasterRequest($event)) {
            return;
        }
        $token = $this->tokenStorage->getToken();
        if (null === $token || $this->authenticationTrustResolver->isAnonymous($token)) {
            return;
        }
        $user = $this->getUserObject();
        if (!$user instanceof User) {
            return;
        }
        $this->connection->update($user->getTable(), ['session' => serialize($this->getSessionBag()->all())], ['id' => $user->id]);
    }