code: protected function didDeliveryCountryChanged(SaleInterface $sale)
      {
          $saleCs = $this->persistenceHelper->getChangeSet($sale);
  
          // Watch for delivery country change
          $oldCountry = $newCountry = null;
  
          // Resolve the old tax resolution target country
          $oldSameAddress = isset($saleCs['sameAddress']) ? $saleCs['sameAddress'][0] : $sale->isSameAddress();
          if ($oldSameAddress) {
              $oldAddress = isset($saleCs['invoiceAddress']) ? $saleCs['invoiceAddress'][0] : $sale->getInvoiceAddress();
          } else {
              $oldAddress = isset($saleCs['deliveryAddress']) ? $saleCs['deliveryAddress'][0] : $sale->getDeliveryAddress();
          }
          if (null !== $oldAddress) {
              $oldAddressCs = $this->persistenceHelper->getChangeSet($oldAddress);
              $oldCountry = isset($oldAddressCs['country']) ? $oldAddressCs['country'][0] : $oldAddress->getCountry();
          }
  
          // Resolve the new tax resolution target country
          $newAddress = $sale->isSameAddress() ? $sale->getInvoiceAddress() : $sale->getDeliveryAddress();
          if (null !== $newAddress) {
              $newCountry = $newAddress->getCountry();
          }
  
          if ($oldCountry !== $newCountry) {
              return true;
          }
  
          return false;
      }
docs: Returns whether the delivery country changed.
  
  @param SaleInterface $sale
  
  @return bool