MSI-1542: Provide MSI support for Shipment Web API endpoint

Author: IvanPletnyov

app/code/Magento/Sales/Test/Unit/Model/Order/ShipmentDocumentFactoryTest.php

@@ -140,9 +140,7 @@ public function testCreate()
         $packages = [];
         $items = [1 => 10];
 
-        $this->extensionAttributeProcessorMock->expects($this->once())
-            ->method('execute')
-            ->with($this->shipmentMock, null);
+        $this->extensionAttributeProcessorMock->expects($this->never())->method('execute');
         $this->itemMock->expects($this->once())->method('getOrderItemId')->willReturn(1);
         $this->itemMock->expects($this->once())->method('getQty')->willReturn(10);
         $this->itemMock->expects($this->once())