Gateway does not deduplicate variables

[hannesj]

When using a federated graph gateway, variable definitions in the query should be deduplicated.

When sending the following query to the gateway:

query TestQuery($size: Int!){
  me {
    id
    name
    profilePicture(size:$size)
    backgroundImage(size:$size)
  }
}

It sends the following query downstream to the service providing me. Note the duplicated size variable definition.

query ($size: Int, $size: Int) {
  me {
    id
    name
    profilePicture(size: $size)
    backgroundImage(size: $size)
  }
}

[hannesj]

Should probably done here

[jbaxleyiii]

@hannesj thanks for the report and the fix!