code: private function getVatRateIdentifier(array $entry)
      {
          /**
           * @var null|Tax $taxModel
           */
          $taxModel = $this->taxRepository->findOneBy(['tax' => $entry['taxRate']]);
  
          if (null === $taxModel) {
              throw new InvalidArgumentException('no matching tax rate found - ' . $entry['taxRate']);
          }
  
          $entry['taxId'] = $taxModel->getId();
  
          $vatRateIdentity = $this->identityService->findOneBy([
              'adapterIdentifier' => (string) $entry['taxId'],
              'adapterName' => ShopwareAdapter::NAME,
              'objectType' => VatRate::TYPE,
          ]);
  
          if (null === $vatRateIdentity) {
              throw new NotFoundException('missing vat rate identity for taxId ' . $entry['taxId']);
          }
  
          return $vatRateIdentity->getObjectIdentifier();
      }
docs: @param array $entry
  
  @return null|string