Developer Replaces Basic Auth with JWT and OAuth2 in Spring Security App

A developer has upgraded a Spring Security application by replacing HTTP Basic Authentication with JWT-based login and OAuth2 support. Under the old setup, raw credentials were sent with every request using only base64 encoding, offering no token expiry or proper logout mechanism. The new flow issues a signed JWT upon login, which carries user identity and role claims and is validated on each subsequent request via a custom filter. OAuth2 login was also integrated, automatically creating a local user record with a default role on first sign-in, ensuring both authentication paths feed into the same role-based access control system. The developer also implemented distinct error responses to differentiate expired tokens from invalid ones, improving client-side handling of authentication failures.