AppserverIo\Appserver\ServletEngine\Http\Request::getProposedSessionId PHP Method

    public function getProposedSessionId()
    {
        // if no session has already been load, initialize the session manager
        /** @var \AppserverIo\Appserver\ServletEngine\SessionManagerInterface $manager */
        $manager = $this->getContext()->search('SessionManagerInterface');
        // if no session manager was found, we don't support sessions
        if ($manager == null) {
            return;
        }
        // if we can't find a requested session name, we try to load the default session cookie
        if ($this->getRequestedSessionName() == null) {
            $this->setRequestedSessionName($manager->getSessionSettings()->getSessionName());
        }
        // load the requested session ID and name
        $sessionName = $this->getRequestedSessionName();
        $id = $this->getRequestedSessionId();
        // try to load session ID from session cookie of request/response
        $cookieFound = null;
        if ($id == null && $this->getResponse()->hasCookie($sessionName)) {
            $cookieFound = $this->getResponse()->getCookie($sessionName);
        } elseif ($id == null && $this->hasCookie($sessionName)) {
            $cookieFound = $this->getCookie($sessionName);
        }
        // check if we can find a cookie
        if (is_array($cookieFound)) {
            // iterate over the cookies and try to find one that is not expired
            foreach ($cookieFound as $cookie) {
                if ($cookie instanceof CookieInterface && $cookie->isExpired() === false) {
                    $this->setRequestedSessionId($id = $cookie->getValue());
                }
            }
            // if we found a single cookie instance
        } elseif ($cookieFound instanceof CookieInterface && $cookieFound->isExpired() === false) {
            $this->setRequestedSessionId($id = $cookieFound->getValue());
        }
        // return the requested session
        return $id;
    }