Apollo Federation Reference resolver with nested fields doesn't work if parent field is non nullable

[darren-clark]

Is there an existing issue for this?

• I have searched the existing issues

Product

Hot Chocolate

Describe the bug

When an entity key includes fields of fields, the ArgumentParser fails if any object type fields are required.

Steps to reproduce

schema:

type Entity @key(fieldset: "type detail { id }") {
  id: ID!
  type: EntityType!
  detail: Detail!
}

enum EntityType {
 TYPE_A
 TYPE_B
}
type Detail {
 id: ID!
}

[ReferenceResolver]
public static Entity Resolve(EntityType entityType,  [Map("detail.id")] string detailId)
....

detailId will always be null, with no error from the pipeline

However if Entity is defined as:

type Entity @key(fieldset: "type detail { id }") {
  id: ID!
  type: EntityType!
  detail: Detail
}

where detail is optional, then it works.

Relevant log output

No response

Additional Context?

Somewhat related to #6232 , only in this case it's the IType parameter that isn't being properly handled.

If type is NonNullType it fails the type check at

                if (type is not IComplexOutputType complexType ||
                    !complexType.Fields.TryGetField(current, out var field))

Version

13.5.1