private function validateBasketContentBuyable(TShopBasketArticle $oBasketArticle, $sMessageManager)
    {
        $bValid = true;
        if (false === $oBasketArticle->IsBuyable()) {
            $oMessage = TCMSMessageManager::GetInstance();
            $aErrorCodes = $oBasketArticle->GetSQLWithTablePrefix();
            $oMessage->AddMessage($sMessageManager, 'ERROR-ADD-TO-BASKET-ARTICLE-NOT-BUYABLE', $aErrorCodes);
            if ($this->IsInList($oBasketArticle)) {
                $this->RemoveArticle($oBasketArticle);
            }
            $bValid = false;
        }

        return $bValid;
    }