Worked on stabilizing authentication flows in the cloudfoundry/uaa repository by addressing a regression in external OAuth role mapping. Focused on correcting how authorities are set and validated during authentication, which reduced the risk of mis-assigned roles and unauthorized access. Updated both unit and integration tests to align with the new authority handling, ensuring future changes would not reintroduce the issue. Utilized Java for back end development and comprehensive unit testing to reinforce the reliability of OAuth flows. This work improved security and reliability for clients relying on UAA for authentication and authorization, with a targeted fix rather than new feature development.