During April 2025, Hyeonggeun Han focused on improving the maintainability of the spring-projects/spring-framework repository by refactoring the test suite for JpaTransactionManager. Han consolidated redundant mock configurations in JpaTransactionManagerTests.java, specifically removing repeated patterns such as given(manager.getTransaction()).willReturn(tx), which reduced boilerplate and streamlined the test setup. This work leveraged Java and advanced mocking frameworks, with an emphasis on unit testing and refactoring best practices. By cleaning up the test code, Han enabled easier onboarding for new contributors and facilitated faster iteration on future tests, demonstrating a thoughtful approach to long-term code quality and maintainability within the project.