Piwik\Tracker\Visit::setIdVisitorForExistingVisit PHP Method

    private function setIdVisitorForExistingVisit($valuesToUpdate)
    {
        // Might update the idvisitor when it was forced or overwritten for this visit
        if (strlen($this->visitProperties->getProperty('idvisitor')) == Tracker::LENGTH_BINARY_ID) {
            $binIdVisitor = $this->visitProperties->getProperty('idvisitor');
            $valuesToUpdate['idvisitor'] = $binIdVisitor;
        }
        // User ID takes precedence and overwrites idvisitor value
        $userId = $this->request->getForcedUserId();
        if ($userId) {
            $userIdHash = $this->request->getUserIdHashed($userId);
            $binIdVisitor = Common::hex2bin($userIdHash);
            $this->visitProperties->setProperty('idvisitor', $binIdVisitor);
            $valuesToUpdate['idvisitor'] = $binIdVisitor;
        }
        return $valuesToUpdate;
    }