In May 2025, Hsu Hweek modernized temporary directory handling across the payara/Payara and vespa-engine/vespa repositories by standardizing temp-dir creation with Java NIO. He refactored critical code paths to use Files.createTempDirectory, replacing custom implementations and reducing boilerplate. This approach improved reliability, error handling, and maintainability, while enabling safer parallel operations and cleaner API surfaces. Working primarily in Java, Hsu focused on robust refactoring and API design, updating method signatures and call sites to streamline usage. The changes addressed cross-repository consistency, mitigated temp-dir related failures, and laid the groundwork for future enhancements, demonstrating depth in Core Java and file I/O.