Generics without requirement of ToSchema?

[0x009922]

Hi! Fantastic project!

I am facing a problem when I define some helper types-wrappers, like axum::Json<T>:

struct EncodeHex<T>(T);

where T might be any type, not implementing ToSchema. I then define a custom impl Serialize and that's it. I would like it to be presented in OpenAPI as just EncodeHex container, without any notion of the generic argument. For example: "EncodeHex - generic container for some value, encoded as a hex."

Problems:

• I could not derive ToSchema for this type, as it would require T: ToSchema, which breaks things for me.
• I could implement ToSchema myself, but then the problem appears in places where I refer to EncodeHex<T>:

#[derive(ToSchema, Serialize)]
struct Transaction {
  payload: EncodeHex<SomeBinaryData>
  //                 ^^^^^^^^^^^^^^ the trait bound `SomeBinaryData: ToSchema` is not satisfied
}

• I could workaround that by adding #[schema(schema_with = EncodeHex::<()>::schema)], but that doesn't work in case of newtypes (i.e. tuple structs) (and the schema isn't automatically recursively included in the global set):

#[derive(Serialize, ToSchema)]
pub struct TransactionRejectionReason(
    // #[schema(schema_with = EncodeHex::<()>::schema)]
    EncodeHex<base::TransactionRejectionReason>,
);

Alternative: put the actual representation value inside of the container instead of T, e.g. EncodeHex(String). Downsides: isn't lazy; loses some type safety; problematic when e.g. T needs to be serialized and it could fail, thus populating the rest of the codebase with the need to handle possible errors. If it is T, the error could be handled when everything is serialized at once, later.

Is there a way to achieve what I want in a clean way?