code: protected function resolveSaleTargetCountry(SaleInterface $sale): ?CountryInterface
      {
          // Get the country from the sale's delivery address
          if (null !== $country = $sale->getDeliveryCountry()) {
              return $country;
          }
  
          // If none, resolves the customer's taxation target address
          if (null !== $customer = $sale->getCustomer()) {
              return $this->resolveCustomerTargetCountry($customer);
          }
  
          return null;
      }
docs: Resolves the sales's taxation target country.
  
  @param SaleInterface $sale
  
  @return CountryInterface|null