MC-43163: [Cloud] [Premier Support] Cannot update only extension attributes via REST (POST: /rest/V1/orders)

Author: valdislav

app/code/Magento/Sales/Model/ResourceModel/EntityAbstract.php

@@ -179,7 +179,9 @@ protected function updateObject(\Magento\Framework\Model\AbstractModel $object)
         $condition = $this->getConnection()->quoteInto($this->getIdFieldName() . '=?', $object->getId());
         $data = $this->_prepareDataForSave($object);
         unset($data[$this->getIdFieldName()]);
-        $this->getConnection()->update($this->getMainTable(), $data, $condition);
+        if (count($data) > 0) {
+            $this->getConnection()->update($this->getMainTable(), $data, $condition);
+        }
     }
 
     /**

dev/tests/api-functional/testsuite/Magento/Sales/Service/V1/OrderUpdateTest.php

@@ -167,6 +167,43 @@ public function testOrderStatusUpdate()
         );
     }
 
+    /**
+     * Check order increment id after updating via webapi
+     *
+     * @magentoApiDataFixture Magento/Sales/_files/order.php
+     */
+    public function testOrderNoAttributesProvidedUpdate()
+    {
+        /** @var Order $order */
+        $order = $this->objectManager->get(Order::class)
+            ->loadByIncrementId(self::ORDER_INCREMENT_ID);
+
+        $entityData = $this->getOrderData($order);
+
+        $requestData = ['entity' => ['entity_id' => $entityData['entity_id']]];
+
+        $serviceInfo = [
+            'rest' => [
+                'resourcePath' => '/V1/orders',
+                'httpMethod' => \Magento\Framework\Webapi\Rest\Request::HTTP_METHOD_POST,
+            ],
+            'soap' => [
+                'service' => self::SERVICE_NAME,
+                'serviceVersion' => self::SERVICE_VERSION,
+                'operation' => self::SERVICE_NAME . 'save',
+            ],
+        ];
+        $result = $this->_webApiCall($serviceInfo, $requestData);
+        $this->assertGreaterThan(1, count($result));
+
+        /** @var Order $actualOrder */
+        $actualOrder = $this->objectManager->get(Order::class)->load($order->getId());
+        $this->assertEquals(
+            $order->getData(OrderInterface::INCREMENT_ID),
+            $actualOrder->getData(OrderInterface::INCREMENT_ID)
+        );
+    }
+
     /**
      * Prepare order data for request
      *