fix openApi attributes to keyset id to present it as a string

The attribute `schema(as = String)` does not result in the expected
behaviour.
It does not convert Id to being represented as a simple string, but
rather simply rename the type `Id` to `String`.

This commit removes the attribute that implements utoipa::ToSchema trait
for type `Id` and adds attribute to all the types that have a keyset id
    as inner type to represent it as string.

crates/cashu/src/nuts/nut00/mod.rs

@@ -116,6 +116,7 @@ pub struct BlindedMessage {
     ///
     /// ID from which we expect a signature.
     #[serde(rename = "id")]
+    #[cfg_attr(feature = "swagger", schema(value_type = String))]
     pub keyset_id: Id,
     /// Blinded secret message (B_)
     ///
@@ -161,6 +162,7 @@ pub struct BlindSignature {
     ///
     /// ID of the mint keys that signed the token.
     #[serde(rename = "id")]
+    #[cfg_attr(feature = "swagger", schema(value_type = String))]
     pub keyset_id: Id,
     /// Blinded signature (C_)
     ///
@@ -240,6 +242,7 @@ pub struct Proof {
     pub amount: Amount,
     /// `Keyset id`
     #[serde(rename = "id")]
+    #[cfg_attr(feature = "swagger", schema(value_type = String))]
     pub keyset_id: Id,
     /// Secret message
     #[cfg_attr(feature = "swagger", schema(value_type = String))]

crates/cashu/src/nuts/nut02.rs

@@ -51,7 +51,6 @@ pub enum Error {
 
 /// Keyset version
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub enum KeySetVersion {
     /// Current Version 00
     Version00,
@@ -88,7 +87,6 @@ impl fmt::Display for KeySetVersion {
 /// which mint or keyset it was generated from.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
 #[serde(into = "String", try_from = "String")]
-#[cfg_attr(feature = "swagger", derive(utoipa::ToSchema), schema(as = String))]
 pub struct Id {
     version: KeySetVersion,
     id: [u8; Self::BYTELEN],
@@ -221,6 +219,7 @@ pub struct KeysetResponse {
 #[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub struct KeySet {
     /// Keyset [`Id`]
+    #[cfg_attr(feature = "swagger", schema(value_type = String))]
     pub id: Id,
     /// Keyset [`CurrencyUnit`]
     pub unit: CurrencyUnit,
@@ -257,6 +256,7 @@ impl From<MintKeySet> for KeySet {
 #[cfg_attr(feature = "swagger", derive(utoipa::ToSchema))]
 pub struct KeySetInfo {
     /// Keyset [`Id`]
+    #[cfg_attr(feature = "swagger", schema(value_type = String))]
     pub id: Id,
     /// Keyset [`CurrencyUnit`]
     pub unit: CurrencyUnit,

crates/cdk-axum/src/lib.rs

@@ -24,7 +24,7 @@ mod swagger_imports {
         BlindSignature, BlindedMessage, CurrencyUnit, PaymentMethod, Proof, Witness,
     };
     pub use cdk::nuts::nut01::{Keys, KeysResponse, PublicKey, SecretKey};
-    pub use cdk::nuts::nut02::{Id, KeySet, KeySetInfo, KeySetVersion, KeysetResponse};
+    pub use cdk::nuts::nut02::{KeySet, KeySetInfo, KeysetResponse};
     pub use cdk::nuts::nut03::{SwapRequest, SwapResponse};
     pub use cdk::nuts::nut04::{
         MintBolt11Request, MintBolt11Response, MintMethodSettings, MintQuoteBolt11Request,
@@ -70,13 +70,11 @@ pub struct MintState {
         ErrorCode,
         ErrorResponse,
         HTLCWitness,
-        Id,
         Keys,
         KeysResponse,
         KeysetResponse,
         KeySet,
         KeySetInfo,
-        KeySetVersion,
         MeltBolt11Request<Uuid>,
         MeltQuoteBolt11Request,
         MeltQuoteBolt11Response<Uuid>,