Nguyen Kim Hieu worked on the hiero-ledger/hiero-sdk-java repository, focusing on improving the quality of the test codebase. He refactored the CustomFeeLimitTest by replacing wildcard imports with explicit imports, which enhanced code readability and maintainability while reducing potential import-related issues. This change also improved static analysis clarity, making future modifications smoother and more consistent with established coding standards. Utilizing Java, JUnit, and unit testing practices, Nguyen ensured that the commit adhered to proper sign-off and review protocols. The work demonstrated attention to detail and commitment to code hygiene, laying a foundation for easier ongoing development and code review.