error: GraphQL object synchronous resolvers are not supported
       · note: https://spec.graphql.org/October2021#sec-Objects
       · note: Specify that this function is async: `async fn foo()`
  --> fail/subscription/field_not_async.rs:12:5
   |
12 |     fn id(&self) -> BoxStream<'static, bool> {
   |     ^^