Upgrading from v1.12 to v1.13 breaks NSwag

[schnerring]

Describe the bug

I upgraded Wolverine in my NSwag playground project, but now get the following error:

System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Namotion.Reflection.GenericTypeContext..ctor(IEnumerable`1 attributes)
   at Namotion.Reflection.ContextualTypeExtensions.ToContextualType(Type type, IEnumerable`1 attributes)
   at NSwag.Generation.AspNetCore.Processors.OperationResponseProcessor.Process(OperationProcessorContext operationProcessorContext)
   at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.RunOperationProcessors(OpenApiDocument document, ApiDescription apiDescription, Type controllerType, MethodInfo methodInfo, OpenApiOperationDescription operationDescription, List`1 allOperations, OpenApiDocumentGenerator generator, OpenApiSchemaResolver schemaResolver)
   at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.AddOperationDescriptionsToDocument(OpenApiDocument document, Type controllerType, List`1 operations, OpenApiDocumentGenerator swaggerGenerator, OpenApiSchemaResolver schemaResolver)
   at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.GenerateApiGroups(OpenApiDocumentGenerator generator, OpenApiDocument document, IGrouping`2[] apiGroups, OpenApiSchemaResolver schemaResolver)
   at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.GenerateAsync(ApiDescriptionGroupCollection apiDescriptionGroups)
   at NSwag.AspNetCore.Middlewares.OpenApiDocumentMiddleware.GenerateDocumentAsync(HttpContext context)
   at NSwag.AspNetCore.Middlewares.OpenApiDocumentMiddleware.GetDocumentAsync(HttpContext context)
   at NSwag.AspNetCore.Middlewares.OpenApiDocumentMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

To Reproduce

I created the PR #684 containing a sample NSwag project that reproduces the issue.

[jeremydmiller]

I pushed through it I think. Same irritation as Swashbuckle. There's all kinds of stuff in NSwag that assumes it's always working with MVC Core