.NET DPG LRO is making an extra GET call to the resource URI, breaking documented response schema

For Sample5_ImportProject.cs in PR #29340, the ImportProject and Train LROs are working as expected based on the session file, but the DeployProject has an extra GET and I can’t tell where it’s coming from. Specifically, the initial LRO request indeed returns a 202 with an Operation-Location to a status monitor:

      "StatusCode": 202,
      "ResponseHeaders": {
        "Access-Control-Expose-Headers": "*",
        "apim-request-id": "3d75422d-f5fe-4bcd-8cdc-c1b240e63a78",
        "Content-Length": "0",
        "Date": "Wed, 15 Jun 2022 01:02:17 GMT",
        "operation-location": "https://languagesdkresource.cognitiveservices.azure.com/language/authoring/analyze-conversations/projects/net-conv-367666463/deployments/production/jobs/ff2585da-967b-41dc-8f05-0a854689e260_637908480000000000?api-version=2022-05-01",
        "request-id": "3d75422d-f5fe-4bcd-8cdc-c1b240e63a78",
        "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload",
        "X-Content-Type-Options": "nosniff",
        "x-envoy-upstream-service-time": "101"
      },
      "ResponseBody": null

The next several requests are what you’d expect - status is running - until the final status update:

    {
      "RequestUri": "https://languagesdkresource.cognitiveservices.azure.com/language/authoring/analyze-conversations/projects/net-conv-367666463/deployments/production/jobs/ff2585da-967b-41dc-8f05-0a854689e260_637908480000000000?api-version=2022-05-01",
      "RequestMethod": "GET",
      "RequestHeaders": {
        "Ocp-Apim-Subscription-Key": "Sanitized",
        "User-Agent": "azsdk-net-AI.Language.Conversations/1.0.0-alpha.20220614.1 (.NET 6.0.5; Microsoft Windows 10.0.22000)",
        "x-ms-client-request-id": "ccc3e9c28c3c019344e0e2ad20829ff8",
        "x-ms-return-client-request-id": "true"
      },
      "RequestBody": null,
      "StatusCode": 200,
      "ResponseHeaders": {
        "Access-Control-Expose-Headers": "*",
        "apim-request-id": "eb1b0550-ca5f-4a97-a177-169f5fdaaad4",
        "Content-Length": "218",
        "Content-Type": "application/json; charset=utf-8",
        "Date": "Wed, 15 Jun 2022 01:02:22 GMT",
        "request-id": "eb1b0550-ca5f-4a97-a177-169f5fdaaad4",
        "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload",
        "X-Content-Type-Options": "nosniff",
        "x-envoy-upstream-service-time": "24"
      },
      "ResponseBody": {
        "jobId": "ff2585da-967b-41dc-8f05-0a854689e260_637908480000000000",
        "createdDateTime": "2022-06-15T01:02:17Z",
        "lastUpdatedDateTime": "2022-06-15T01:02:22Z",
        "expirationDateTime": "2022-06-22T01:02:17Z",
        "status": "succeeded"
      }
    },

But then immediately afterward, there’s this extra GET which is what the Operation<BinaryData>.Value ultimately contains:

    {
      "RequestUri": "https://languagesdkresource.cognitiveservices.azure.com/language/authoring/analyze-conversations/projects/net-conv-367666463/deployments/production?api-version=2022-05-01",
      "RequestMethod": "GET",
      "RequestHeaders": {
        "Ocp-Apim-Subscription-Key": "Sanitized",
        "User-Agent": "azsdk-net-AI.Language.Conversations/1.0.0-alpha.20220614.1 (.NET 6.0.5; Microsoft Windows 10.0.22000)",
        "x-ms-client-request-id": "8c11e8cce5e682c8638a22cdb3087be4",
        "x-ms-return-client-request-id": "true"
      },
      "RequestBody": null,
      "StatusCode": 200,
      "ResponseHeaders": {
        "Access-Control-Expose-Headers": "*",
        "apim-request-id": "35de4d51-fcec-4df0-82ca-c06206d6f36f",
        "Content-Length": "281",
        "Content-Type": "application/json; charset=utf-8",
        "Date": "Wed, 15 Jun 2022 01:02:23 GMT",
        "request-id": "35de4d51-fcec-4df0-82ca-c06206d6f36f",
        "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload",
        "X-Content-Type-Options": "nosniff",
        "x-envoy-upstream-service-time": "22"
      },
      "ResponseBody": {
        "deploymentName": "production",
        "modelId": "Sample5-20220615T010216-aeac9f0032944941b024163bc3ebff89",
        "lastTrainedDateTime": "2022-06-15T01:02:16.6869195Z",
        "lastDeployedDateTime": "2022-06-15T01:02:22Z",
        "deploymentExpirationDate": "2023-10-28",
        "modelTrainingConfigVersion": "2022-05-01"
      }
    }

I can’t tell from where this comes? Why is the LRO querying the actual resource? The generated LRO implementation uses OperationFinalStateVia.Location just like the other aforementioned LROs:

using HttpMessage message = CreateDeployProjectRequest(projectName, deploymentName, content, context);
return LowLevelOperationHelpers.ProcessMessage(_pipeline, message, ClientDiagnostics, "ConversationAnalysisProjectsClient.DeployProject", OperationFinalStateVia.Location, context, waitUntil);

@annelo-msft @AlexanderSher @chunyu3 ? /cc @kristapratico @mshaban-msft @tg-msft @johanste

Some useful links:

• DeployProject LRO: https://github.com/Azure/azure-rest-api-specs/blob/725f4ca360426a32d20e81eb945065e62c285d6a/specification/cognitiveservices/data-plane/Language/stable/2022-05-01/analyzeconversations-authoring.json#L532-L540
• DeployProject status monitor: https://github.com/Azure/azure-rest-api-specs/blob/725f4ca360426a32d20e81eb945065e62c285d6a/specification/cognitiveservices/data-plane/Language/stable/2022-05-01/analyzeconversations-authoring.json#L619-L624
• That final DeployProject resource GET: https://github.com/Azure/azure-rest-api-specs/blob/725f4ca360426a32d20e81eb945065e62c285d6a/specification/cognitiveservices/data-plane/Language/stable/2022-05-01/analyzeconversations-authoring.json#L483-L488

_Originally posted by @heaths in https://github.com/Azure/azure-sdk-for-net/issues/29331#issuecomment-1158191653_

[heaths]

Talking offline, we’ll do @kristapratico’s idea for the CLU 1.0 GA:

@kristapratico did have a good idea for a workaround, though: since we’re already transforming the swagger for autorest to provide the schema for the final object, we could update the resource PUT to include an artificial 200 response with the GET’s response model: “#/definitions/ConversationalAnalysisAuthoringProjectDeployment”.

@annelo-msft I’ll leave it up to you whether you want to keep this issue as a tracking issue for support of this (anti?) pattern.

[annelo-msft]

Based on investigations by @AlexanderSher, @kristapratico, and @lmazuel (thank you all!), we believe the .NET implementation is the same as Python’s implementation and is correct. We make the final GET request because the original request was a PUT, as implemented here: https://github.com/Azure/autorest.csharp/blob/feature/v3/src/assets/Generator.Shared/NextLinkOperationImplementation.cs#L196

Per @lmazuel:

I believe if CLU fills the resourceLocation, all your problems go away and you don’t need any options, see guidelines: https://github.com/microsoft/api-guidelines/blob/8465bf242ad1743beb49caa90a5a36c9190dc648/Guidelines.md#target-resource-location

Since the .NET implementation is correct, we will not make changes to the generator or shared source types.