Worked on enhancing security and reliability in the spring-projects/spring-security repository by addressing a bug in the OAuth2 client flow. Focused on backend development using Java and Spring Security, the work involved modifying both synchronous and reactive paths to ensure that InMemoryOAuth2AuthorizedClientService always retrieves the current ClientRegistration from ClientRegistrationRepository rather than relying on cached data. This change mitigated the risk of using outdated client secrets or configurations during authorization, thereby strengthening the overall security posture. The solution was delivered as an isolated, low-risk commit, demonstrating careful attention to correctness and a strong understanding of OAuth2 workflows within the Java ecosystem.