/**
     * returns user object from forced parameter AffiliateID
     * parameter name is dependent on track.js, where it is used.
     *
     * @return string
     */
    protected function getUserFromForcedParameter(Pap_Contexts_Click $context) {
        $context->debug("  Trying to get affiliate from request parameter '".Pap_Tracking_Request::getForcedAffiliateParamName()."'");

        $userId = $context->getForcedAffiliateId();
        if($userId != '') {
            $context->debug("    Setting affiliate from request parameter. Affiliate Id: ".$userId);
            return $this->getUserById($context, $userId);
        }

        $context->debug('Affiliate not found in forced parameter');
        return null;
    }