MAGETWO-92568: Fatal error during multishipping checkout

Author: OlgaVasyltsun

app/code/Magento/Multishipping/Model/Checkout/Type/Multishipping.php

@@ -170,6 +170,11 @@ class Multishipping extends \Magento\Framework\DataObject
      */
     private $logger;
 
+    /**
+     * @var \Magento\Framework\Api\DataObjectHelper
+     */
+    private $dataObjectHelper;
+
     /**
      * Constructor
      *
@@ -227,7 +232,8 @@ public function __construct(
         \Magento\Quote\Api\Data\CartExtensionFactory $cartExtensionFactory = null,
         AllowedCountries $allowedCountryReader = null,
         Multishipping\PlaceOrderFactory $placeOrderFactory = null,
-        LoggerInterface $logger = null
+        LoggerInterface $logger = null,
+        \Magento\Framework\Api\DataObjectHelper $dataObjectHelper = null
     ) {
         $this->_eventManager = $eventManager;
         $this->_scopeConfig = $scopeConfig;
@@ -258,6 +264,8 @@ public function __construct(
             ->get(Multishipping\PlaceOrderFactory::class);
         $this->logger = $logger ?: ObjectManager::getInstance()
             ->get(LoggerInterface::class);
+        $this->dataObjectHelper = $dataObjectHelper ?: ObjectManager::getInstance()
+            ->get(\Magento\Framework\Api\DataObjectHelper::class);
         parent::__construct($data);
         $this->_init();
     }
@@ -663,7 +671,14 @@ protected function _prepareOrder(\Magento\Quote\Model\Quote\Address $address)
         $quote->reserveOrderId();
         $quote->collectTotals();
 
-        $order = $this->quoteAddressToOrder->convert($address);
+        $order = $this->_orderFactory->create();
+
+        $this->dataObjectHelper->mergeDataObjects(
+            \Magento\Sales\Api\Data\OrderInterface::class,
+            $order,
+            $this->quoteAddressToOrder->convert($address)
+        );
+
         $order->setQuote($quote);
         $order->setBillingAddress($this->quoteAddressToOrderAddress->convert($quote->getBillingAddress()));