public function getCreditNotes()
    {
        $result = null;
        if ($this->getType() === static::Order) {
            $result = array();
            $shopCreditNotes = $this->getShopCreditNotesOrIds();
            foreach ($shopCreditNotes as $shopCreditNote) {
                $result[] = new static(static::CreditNote, $shopCreditNote);
            }
        }
        return $result;
    }