Make Credentials.username optional.

Isn't required for token auth.

core/src/authentication.rs

@@ -28,7 +28,7 @@ impl From<AuthenticationError> for Error {
 /// The credentials are used to log into the Spotify API.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Credentials {
-    pub username: String,
+    pub username: Option<String>,
 
     #[serde(serialize_with = "serialize_protobuf_enum")]
     #[serde(deserialize_with = "deserialize_protobuf_enum")]
@@ -51,15 +51,15 @@ impl Credentials {
     /// ```
     pub fn with_password(username: impl Into<String>, password: impl Into<String>) -> Self {
         Self {
-            username: username.into(),
+            username: Some(username.into()),
             auth_type: AuthenticationType::AUTHENTICATION_USER_PASS,
             auth_data: password.into().into_bytes(),
         }
     }
 
-    pub fn with_access_token(username: impl Into<String>, token: impl Into<String>) -> Self {
+    pub fn with_access_token(token: impl Into<String>) -> Self {
         Self {
-            username: username.into(),
+            username: None,
             auth_type: AuthenticationType::AUTHENTICATION_SPOTIFY_TOKEN,
             auth_data: token.into().into_bytes(),
         }
@@ -144,9 +144,9 @@ impl Credentials {
         let auth_data = read_bytes(&mut cursor)?;
 
         Ok(Self {
-            username,
-            auth_type,
-            auth_data,
+            username: Some(username),
+            auth_type: auth_type,
+            auth_data: auth_data,
         })
     }
 }

core/src/connection/mod.rs

@@ -99,9 +99,9 @@ pub async fn authenticate(
     };
 
     let mut packet = ClientResponseEncrypted::new();
-    packet
-        .mut_login_credentials()
-        .set_username(credentials.username);
+    if let Some(username) = credentials.username {
+        packet.mut_login_credentials().set_username(username);
+    }
     packet
         .mut_login_credentials()
         .set_typ(credentials.auth_type);
@@ -136,7 +136,7 @@ pub async fn authenticate(
             let welcome_data = APWelcome::parse_from_bytes(data.as_ref())?;
 
             let reusable_credentials = Credentials {
-                username: welcome_data.get_canonical_username().to_owned(),
+                username: Some(welcome_data.get_canonical_username().to_owned()),
                 auth_type: welcome_data.get_reusable_auth_credentials_type(),
                 auth_data: welcome_data.get_reusable_auth_credentials().to_owned(),
             };

core/src/session.rs

@@ -162,8 +162,9 @@ impl Session {
             }
         };
 
-        info!("Authenticated as \"{}\" !", reusable_credentials.username);
-        self.set_username(&reusable_credentials.username);
+        let username = reusable_credentials.username.as_ref().expect("Username");
+        info!("Authenticated as \"{}\" !", username);
+        self.set_username(username);
         if let Some(cache) = self.cache() {
             if store_credentials {
                 cache.save_credentials(&reusable_credentials);

examples/get_token.rs

@@ -36,7 +36,7 @@ async fn main() {
 
     // Now create a new session with that token.
     let session = Session::new(session_config, None);
-    let credentials = Credentials::with_access_token(username, token.access_token);
+    let credentials = Credentials::with_access_token(token.access_token);
     println!("Connecting with token..");
     match session.connect(credentials, false).await {
         Ok(()) => println!("Session username: {:#?}", session.username()),