No SDL found in response from federated service.

I'm having an issue with pushing our federated schema to the schema registry.

I am trying to push the schema as part of our CI/CD using the command detailed [here](https://www.apollographql.com/docs/federation/managed-federation/setup/#2-register-all-implementing-service-schemas). I've tested the command and it works when we have the service running locally and we are using the `--endpoint` argument. However, we want to use the `--localSchemaFile` argument. Our service is in Python and we're using `graphene-federation`. In order to generate the schema file, we're using `graphene`'s [management command](https://docs.graphene-python.org/projects/django/en/latest/introspection/#graphql-sdl-representation) which outputs the schema to either `.json` or `.graphql` . When we provide the generated localSchemaFile in either format we get this error:

```
Error: No SDL found in response from federated service. This means that the federated service exposed a `__service` field that did not emit errors, but that did not contain a spec-compliant `sdl` field.
```

Here is the [schema.graphql](https://gist.github.com/Hilaryous/b2b7102515ff09c3bf22a3a321d7155e) and the [schema.json](https://gist.github.com/Hilaryous/6da5d8cb381a25646dc11ebfa0408df1) and here is the `apollo` cli command I am running:

```
npx apollo service:push
--graph={{ apollo_graph_name }}
--key={{ apollo_key }}
--variant=dev
--localSchemaFile=schema.graphql
--serviceName={{ service name }}
--serviceURL=http://{{service_url}}/graphql/

```

Seem like our schema is compliant to the spec, not sure what we're missing. Maybe it's an issue with how the schema file is generated?

Start with the documented `apollo service:push` command and its `--localSchemaFile` handling, using the provided `schema.graphql` and `schema.json` as inputs. Compare both generated representations with the linked federation setup documentation and determine why the command reports no SDL; done means the supplied schema can be pushed without that error.

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