Removing all mutations from subgraphs doesn't remove the Mutation type from the supergraph schema

Product

Hot Chocolate

Version

14.2.0

Link to minimal reproduction

https://github.com/scottstubbs/HotChocolate-Fusion-Hide-Mutations

Steps to reproduce

To run the solution:

1. Run dotnet tool restore
2. Build HotChocolate-Fusion-Mutations.sln
3. Run all projects (Gateway, Owners and Cars) in the solution
4. Open https://localhost:50000/graphql in a browser
5. Create a new document in Nitro

At this point the introspection fails.

To make changes to the subgraphs, rebuild the gateway from the root directory:

• Run ./Fuse.ps1 to pack and compose all projects OR
• Run ./Fuse.ps1 -Project {ProjectFolder} to pack and compose a specific project

What is expected?

Introspection should succeed. The Mutation type should be gone from the supergraph schema.

What is actually happening?

Introspection fails and the error is logged to the Nitro console and the Visual Studio Output window.

Relevant log output

info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:50000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\users\sstubbs\source\repos\ReadOnly\Gateway
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
      HotChocolate.SchemaException: For more details look at the `Errors` property.

      1. The object type `Mutation` has to at least define one field in order to be valid. (HotChocolate.Types.ObjectType)

         at HotChocolate.SchemaBuilder.Setup.CompleteSchema(SchemaBuilder builder, IDescriptorContext context, LazySchema lazySchema, TypeRegistry typeRegistry)
         at HotChocolate.SchemaBuilder.Setup.Create(SchemaBuilder builder, LazySchema lazySchema, IDescriptorContext context)
         at HotChocolate.SchemaBuilder.Create(IDescriptorContext context)
         at HotChocolate.SchemaBuilder.HotChocolate.ISchemaBuilder.Create(IDescriptorContext context)
         at HotChocolate.Execution.RequestExecutorResolver.CreateSchemaAsync(ConfigurationContext context, RequestExecutorSetup setup, RequestExecutorOptions executorOptions, IServiceProvider schemaServices, TypeModuleChangeMonitor typeModuleChangeMonitor, CancellationToken cancellationToken)
         at HotChocolate.Execution.RequestExecutorResolver.CreateSchemaServicesAsync(ConfigurationContext context, RequestExecutorSetup setup, CancellationToken cancellationToken)
         at HotChocolate.Execution.RequestExecutorResolver.GetRequestExecutorNoLockAsync(String schemaName, CancellationToken cancellationToken)
         at HotChocolate.Execution.RequestExecutorResolver.GetRequestExecutorAsync(String schemaName, CancellationToken cancellationToken)
         at HotChocolate.Execution.RequestExecutorProxy.GetRequestExecutorAsync(CancellationToken cancellationToken)
         at HotChocolate.AspNetCore.HttpGetSchemaMiddleware.HandleRequestAsync(HttpContext context)
         at HotChocolate.AspNetCore.HttpGetSchemaMiddleware.InvokeAsync(HttpContext context)
         at HotChocolate.AspNetCore.HttpGetMiddleware.InvokeAsync(HttpContext context)
         at HotChocolate.AspNetCore.HttpMultipartMiddleware.InvokeAsync(HttpContext context)
         at HotChocolate.AspNetCore.HttpPostMiddlewareBase.InvokeAsync(HttpContext context)
         at Microsoft.AspNetCore.Builder.EndpointRouteBuilderExtensions.<>c__DisplayClass23_0.<<UseCancellation>b__1>d.MoveNext()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

Additional context

This happens because all subgraph mutations were marked with the [Internal] attribute. The fusion compose command doesn't remove the empty Mutation type from the supergraph schema. The same result happens when using the [Tag(name: "internal")] attribute.

Start with the linked minimal reproduction: restore its dotnet tools, build HotChocolate-Fusion-Mutations.sln, and compose the gateway with Fuse.ps1. Check the fusion compose output and the gateway schema during Nitro introspection; done means introspection succeeds and the empty Mutation type is absent from the supergraph.