Directives on QUERY, MUTATION, or SUBSCRIPTION are not passed to subgraphs

[lleadbet]

Describe the bug

When using a directive that uses one of QUERY, MUTATION, or SUBSCRIPTION, the router strips it before sending the request to the subgraph.

To Reproduce

Given the below two subgraphs:

Subgraph 1:

directive @operation on MUTATION | QUERY | SUBSCRIPTION
directive @field on FIELD

type Foo @key(fields: "id") {
  id: ID!
}
type Query {
  foo: [Foo]
}

Subgraph 2:

directive @operation on MUTATION | QUERY | SUBSCRIPTION
directive @field on FIELD

type Foo @key(fields: "id") {
  id: ID!
  bar: String
}

It will generate the following query plan:

QueryPlan {
  Sequence {
    Fetch(service: "foo") {
      {
        foo @field {
          __typename
          id
        }
      }
    },
    Flatten(path: "foo.@") {
      Fetch(service: "bar") {
        {
          ... on Foo {
            __typename
            id
          }
        } =>
        {
          ... on Foo {
            bar @field
          }
        }
      },
    },
  },
}

With this query:

query Operation @operation{
  foo @field {
    bar @field
  }
}

We can see that the FIELD directive works, however the one using the operation-level location is not.

Expected behavior

The operation-level directives are persisted to the initial subgraph.

[abernix]

@lleadbet We moved this to the federation repository as this appears to be a query planner issue (i know you know this, but for broad context: query planner runs inside the router, but lives in this repo right now)

[duckki]

I merged the PR (#2967) that fixes this issue.