Stable OData EDM 9.0.0 still breaks OpenAPI conversion with MissingMethodException (GetReturn) #937

Summary

Microsoft.OpenApi.OData 3.2.1 fails at runtime with stable Microsoft.OData.Core / Microsoft.OData.Edm 9.0.0. This blocks updating the Kiota sample API's OData dependencies while migrating to .NET 11.

Related: #833 describes the same missing-method failure with 9.0.0-rc and anticipates a subsequent release restoring compatibility. This report confirms the failure with the published stable 9.0.0 package.

Reproduction

The affected sample is https://github.com/microsoft/kiota-samples/tree/main/sample-api/api. Update its target to net11.0 and use:

Generate an EDM model and convert it as the sample's OpenApiController does:

var builder = new ODataConventionModelBuilder();
builder.EnableLowerCamelCase();
builder.EntitySet<ToDoItem>("ToDoItems");
var model = builder.GetEdmModel();
var document = model.ConvertToOpenApi(new OpenApiConvertSettings
{
    ServiceRoot = new Uri("https://localhost:7206/"),
    EnableKeyAsSegment = true,
    PrefixEntityTypeNameBeforeKey = true
});

Requesting /openapi/openapi.yaml returns HTTP 500. A WebApplicationFactory integration test reproduces it. The sample's existing 10 CRUD/query tests pass with these versions; the new OpenAPI endpoint test fails.

Actual result

System.MissingMethodException: Method not found: 'Microsoft.OData.Edm.IEdmOperationReturn Microsoft.OData.Edm.ExtensionMethods.GetReturn(Microsoft.OData.Edm.IEdmOperation)'.
   at Microsoft.OpenApi.OData.Edm.ODataPathProvider.RetrieveBoundOperationPaths(OpenApiConvertSettings convertSettings)
   at Microsoft.OpenApi.OData.Edm.ODataPathProvider.GetPaths(IEdmModel model, OpenApiConvertSettings settings)
   at Microsoft.OpenApi.OData.Edm.ODataContext.LoadAllODataPaths()+MoveNext()
   at Microsoft.OpenApi.OData.Edm.ODataContext.get_AllPaths()
   at Microsoft.OpenApi.OData.Generator.OpenApiPathItemGenerator.AddPathItemsToDocument(ODataContext context, OpenApiDocument document)
   at Microsoft.OpenApi.OData.EdmModelOpenApiExtensions.ConvertToOpenApi(IEdmModel model, OpenApiConvertSettings settings)

Expected result

A published converter version compatible with stable OData EDM 9.0.0 should generate the sample's OpenAPI description without a missing-method exception. Please clarify the supported combination and release plan for OData 9 compatibility.

Environment

• .NET SDK 11.0.100; ASP.NET Core runtime 11.0.0
• Windows ARM64
• Latest published Microsoft.OpenApi.OData package available from the configured NuGet source: 3.2.1

The dependent update is microsoft/kiota-samples#9360. Keeping ASP.NET Core OData 9.5.0 is not an alternative for Core 9, because it constrains Core/EDM to < 9.0.0.