code: private function getCustomerGroupFromPrice(Price $price)
      {
          $repository = $this->entityManager->getRepository(GroupModel::class);
  
          if (null === $price->getCustomerGroupIdentifier()) {
              return $repository->findOneBy(['key' => 'EK']);
          }
  
          $identity = $this->identityService->findOneBy(
              [
                  'objectIdentifier' => (string) $price->getCustomerGroupIdentifier(),
                  'objectType' => CustomerGroup::TYPE,
                  'adapterName' => ShopwareAdapter::NAME,
              ]
          );
  
          if (null === $identity) {
              return null;
          }
  
          return $repository->find($identity->getAdapterIdentifier());
      }
docs: @param Price $price
  
  @return null|GroupModel