code: protected function updateExchangeRate(SupplierOrderInterface $order)
      {
          // TODO Remove when supplier order payments will be implemented.
          if (null !== $order->getExchangeRate()) {
              return false;
          }
  
          if (!SupplierOrderStates::isStockableState($order->getState())) {
              return false;
          }
  
          $date = new \DateTime();
  
          $rate = $this->currencyConverter->getRate(
              $this->currencyConverter->getDefaultCurrency(),
              $order->getCurrency()->getCode(),
              $date
          );
  
          $order
              ->setExchangeRate($rate)
              ->setExchangeDate($date);
  
          return true;
      }
docs: Updates the order exchange rate.
  
  @param SupplierOrderInterface $order
  
  @return bool Whether the payment has been changed or not.