add handle field to shipping lines

fixtures/shippinglines/requested_fulfillment_service_id_null.json

@@ -38,5 +38,6 @@
     }
   ],
   "carrier_identifier": "third_party_carrier_identifier",
-  "requested_fulfillment_service_id": null
+  "requested_fulfillment_service_id": null,
+  "handle": "test"
 }

fixtures/shippinglines/requested_fulfillment_service_id_number.json

@@ -38,5 +38,6 @@
     }
   ],
   "carrier_identifier": "third_party_carrier_identifier",
-  "requested_fulfillment_service_id": 123456
+  "requested_fulfillment_service_id": 123456,
+  "handle": "test"
 }

fixtures/shippinglines/valid.json

@@ -38,5 +38,6 @@
     }
   ],
   "carrier_identifier": "third_party_carrier_identifier",
-  "requested_fulfillment_service_id": "third_party_fulfillment_service_id"
+  "requested_fulfillment_service_id": "third_party_fulfillment_service_id",
+  "handle": "test"
 }

order.go

@@ -402,6 +402,7 @@ type ShippingLines struct {
 	DeliveryCategory              string           `json:"delivery_category,omitempty"`
 	CarrierIdentifier             string           `json:"carrier_identifier,omitempty"`
 	TaxLines                      []TaxLine        `json:"tax_lines,omitempty"`
+	Handle                        string           `json:"handle,omitempty"`
 }
 
 // UnmarshalJSON custom unmarshaller for ShippingLines implemented to handle requested_fulfillment_service_id being

order_test.go

@@ -1161,6 +1161,10 @@ func testShippingLines(t *testing.T, expected, actual ShippingLines) {
 		t.Errorf("ShippingLines.CarrierIdentifier should be (%v), was (%v)", expected.CarrierIdentifier, actual.CarrierIdentifier)
 	}
 
+	if actual.Handle != expected.Handle {
+		t.Errorf("ShippingLines.Handle should be (%v), was (%v)", expected.Handle, actual.Handle)
+	}
+
 	testTaxLines(t, expected.TaxLines, actual.TaxLines)
 }
 
@@ -1346,5 +1350,6 @@ func validShippingLines() ShippingLines {
 				Rate:  &tl2Rate,
 			},
 		},
+		Handle: "test",
 	}
 }