Fix Magento\Sales\Service\V1\ShipmentGetTest::testShipmentGet

[p-bystritsky]

Preconditions

1. Magento 2 with MSI.

Steps to reproduce

1. Run test Magento\Sales\Service\V1\ShipmentGetTest::testShipmentGet.

Expected result

1. Test run finished without any errors.

Actual result

1. Test run fails.

Note

Fail is caused by direct comparison of "extension_attributes" field of Shipment record loaded from database and Shipment information returned by API call.

[denteblu]

already in progress in #1155