Federation @join__field requires parameter handling improvement

[aarne]

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---

Describe the bug

Given this snipped from a working supergraph schema.

type Environment {
  id: ID!
}

type Whatever {
  id: ID!
  environment: Environment! @join__field(graph: ACCOUNTS)  @join__field(graph: LOCAL, external: true) 
  external1: String @join__field(graph: LOCAL, requires: "id environment {id}") 
  external2: String @join__field(graph: LOCAL, requires: "id environment{id}") 
}

The resolver for external1 will receive the required fields correctly. But external2 will get only the id field correctly filled. The difference is only the space.

Not sure what is the best way to fix this, but i assume this is driven from utils/getKeyFnForFederation. The function considers the first level keys (split by space) only.

I think we have 2 options:

• keep current simple logic and split the key until first { - will still give you the whole subtree (might be more data than needed)
• we could parse the whole selectionSet and recursively filter the root value.