Yan enhanced the reliability and security of JAR file processing across the corretto/corretto-8, corretto-11, corretto-17, and corretto-21 repositories by refining how multiple MANIFEST.MF entries are handled. Using Java, Yan focused on API design and code refactoring to standardize warning messages and ensure that malformed JARs are consistently treated as unsigned. The work involved resetting verification components to prevent incorrect signature validation and introducing clear, maintainable warning paths. These targeted bug fixes improved artifact handling and reduced ambiguity in signature verification, demonstrating a thoughtful approach to robust Java development and cross-repository API refinement within the Corretto project.