error: GraphQL object does not allow fields with the same name
  --> $DIR/impl_fields_unique.rs:9:5
   |
9  | /     fn test(&self) -> String {
10 | |         String::new()
11 | |     }
   | |_____^
   |
   = help: There is at least one other field with the same name `test`, possibly renamed via the #[graphql] attribute
   = note: https://spec.graphql.org/June2018/#sec-Objects