Recursive object with multiple properties with same type leads to fatal exception

[RealGoodAnthony]

Describe the issue
When attempting to respond with a model that has a recursive object reference there is a side effect where other properties can no longer carry the same type.

For example:

public sealed class GroupModel
{
    public GroupModel? ChildGroup { get; set; }
    public UserModel? Owner { get; set; }
    public UserModel? CoOwner { get; set; }
}

public sealed class UserModel
{
    public Guid Id { get; set; }
}

In the example above, a group can have a child group, an owner, and a co-owner. This leads to the following exception when attempting to generate the Swagger:

An item with the same key has already been added. Key: userModel

   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Visitors.RecursiveObjectTypeVisitor.ProcessProperties(IOpenApiSchemaAcceptor instance, String schemaName, Dictionary`2 properties, NamingStrategy namingStrategy)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Visitors.RecursiveObjectTypeVisitor.Visit(IAcceptor acceptor, KeyValuePair`2 type, NamingStrategy namingStrategy, Attribute[] attributes)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Visitors.OpenApiSchemaAcceptor.Accept(VisitorCollection collection, NamingStrategy namingStrategy)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.DocumentHelper.GetOpenApiSchemas(List`1 elements, NamingStrategy namingStrategy, VisitorCollection collection)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Document.Build(Assembly assembly, OpenApiVersionType version)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiTriggerFunctionProvider.RenderSwaggerDocument(HttpRequest req, String extension, ExecutionContext ctx, ILogger log)

However, if you remove the ChildGroup from the GroupModel definition, the exception disappears. You can also get rid of the exception by removing either Owner or CoOwner from the definition.

To Reproduce
Full repro steps and a sample project have been outlined here: https://github.com/RealGoodAnthony/OpenApiBugRepro

Expected behavior
The Swagger JSON and UI are rendered successfully.

[RealGoodAnthony]

I think I see the problem, but I'm not sure. I'd be happy to submit a patch with some guidance. When looking at the difference between RecursiveObjectTypeVisitor and ObjectTypeVisitor, I noticed a minor difference in these two lines of code:

• RecursiveObjectTypeVisitor
• ObjectTypeVisitor

I'm thinking that the reason this happens for recursive object types and not for object types is the difference in those two lines. Notably, the ObjectTypeVisitor groups by the title of the schema object to prevent issues with duplicate keys. There are also some other minor differences, but I'm not entirely sure what to make of them frankly.

[RealGoodAnthony]

@justinyoo Do you think this is a bug that will be addressed soon? I am happy to make a PR, but I'm worried I may be missing something.

[justinyoo]

@RealGoodAnthony Thanks for the issue! I'm looking at the issue and will add a PR for it soon.