fix: handle discovery response with and without ucp wrapper

The latest samples server (01-23) returns profile fields at the top
level without a "ucp" wrapper key. Older servers wrap under {"ucp": {...}}.
Use data.get("ucp", data) to handle both formats.

Also adds required id and line_item_ids fields to fulfillment method
and group in create payload (required by latest server).

Author: sbeashwar

integration_test_utils.py

@@ -394,7 +394,7 @@ def shopping_service_endpoint(self) -> str:
       discovery_resp = self.client.get("/.well-known/ucp")
       self.assert_response_status(discovery_resp, 200)
       data = discovery_resp.json()
-      profile = BusinessSchema(**data["ucp"])
+      profile = BusinessSchema(**(data.get("ucp", data)))
       rdn = ReverseDomainName(root="dev.ucp.shopping")
       service_list = profile.services.get(rdn)
       if not service_list:
@@ -502,9 +502,12 @@ def create_checkout_payload(
         )
       )
       group = fulfillment_group_create_req.FulfillmentGroupCreateRequest(
+        id="group_1",
+        line_item_ids=[],
         selected_option_id="std-ship"
       )
       method = fulfillment_method_create_req.FulfillmentMethodCreateRequest(
+        id="method_1",
         type="shipping",
         line_item_ids=[],
         destinations=[destination],

protocol_test.py

@@ -87,7 +87,7 @@ def test_discovery_urls(self):
     response = self.client.get("/.well-known/ucp")
     self.assert_response_status(response, 200)
     data = response.json()
-    profile = BusinessSchema(**data["ucp"])
+    profile = BusinessSchema(**(data.get("ucp", data)))
 
     url_entries = self._extract_document_urls(profile)
     failures = []
@@ -146,7 +146,7 @@ def test_discovery(self):
     data = response.json()
 
     # Validate schema using SDK model
-    profile = BusinessSchema(**data["ucp"])
+    profile = BusinessSchema(**(data.get("ucp", data)))
 
     self.assertIn(
       profile.version.root,
@@ -227,7 +227,7 @@ def test_version_negotiation(self):
     discovery_resp = self.client.get("/.well-known/ucp")
     self.assert_response_status(discovery_resp, 200)
     discovery_data = discovery_resp.json()
-    profile = BusinessSchema(**discovery_data["ucp"])
+    profile = BusinessSchema(**(discovery_data.get("ucp", discovery_data)))
     rdn = ReverseDomainName(root="dev.ucp.shopping")
     shopping_services = profile.services[rdn]
     rest_binding = next(