code: public function onInitialize(ResourceEventInterface $event)
      {
          $sale = $this->getSaleFromEvent($event);
  
          if (null !== $customer = $sale->getCustomer()) {
              $invoiceDefault = $customer->getDefaultInvoiceAddress(true);
              $deliveryDefault = $customer->getDefaultDeliveryAddress(true);
  
              if (null === $sale->getInvoiceAddress() && null !== $invoiceDefault) {
                  $sale->setInvoiceAddress(
                      $this->saleFactory->createAddressForSale($sale, $invoiceDefault)
                  );
              }
  
              if (null === $sale->getDeliveryAddress() && null !== $deliveryDefault && $deliveryDefault !== $invoiceDefault) {
                  $sale
                      ->setSameAddress(false)
                      ->setDeliveryAddress(
                          $this->saleFactory->createAddressForSale($sale, $invoiceDefault)
                      );
              }
          }
      }
docs: Initialize event handler.
  
  @param ResourceEventInterface $event