[Fusion] Endless Loop if subgraph does not have any types declared

[tessarolli]

Is there an existing issue for this?

• I have searched the existing issues

Product

Hot Chocolate

Describe the bug

If you have a subgraph which doesnt have any types declared in its schema, like the following:

schema {
  query: Query
  mutation: Mutation
}

type Mutation {
  flightServiceMutationTest: Boolean!
}

type Query {
  flightServiceQueryTest: Boolean!
}

And you compose it on a Fusion Gateway and you query for any valid query or mutation on that subgraph, you will trigger an endless loop on
ExecutionStepDiscoveryMiddleware
Because that Subgraph wont be referenced in FusionGraphConfiguration .

Steps to reproduce

Relevant log output

No response

Additional Context?

If you modify the schema to something that includes an Custom Type, like the one below, then it works.

schema {
  query: Query
  mutation: Mutation
}

type Mutation {
  flightServiceMutationTest: Boolean!
}

type Query {
  flightServiceQueryTest: Boolean!
  myProperty: TestType!
}

type TestType {
  myProperty: Int!
}

Version

13.6.0-preview.7