Ktor server - how to make request extensions accessible to queries/mutations

[astevens-remitly]

I'm working on a federated subgraph using the ktor server and I'm expecting some user data to be passed into the request in the extensions field. I'll want to be able to access the custom field from my queries/mutations and I'm not finding a good way to do that. Any ideas?

Dummy request body:

{
  "query": ...
  "operationName": ...
  "variables": ...
  "extensions": { 
      "myCustomFields": { 
          "myField1": "myCustomData1",  
          "myField2": "myCustomData2" 
      } 
    }
}

This is kind of how I'm imagining it would be used.

class MyMutations: Mutation {
   fun myMutation(): SomeResponse { 
     val myField1 = ?? somehow get "myCustomData1" from the extensions
     ...
   }
}

I would have guessed that the best place to get this information would in the graphql context, but I'm not seeing an easy way to do that since the extensions are only available after parsing and the context generator doesn't use a parsed request.