Worked on the apache/httpcomponents-client repository to enhance the reliability of the H2SharingConnPool component by addressing a concurrency issue related to connection pool management. Developed a targeted unit test in Java to verify that releasing an already-released PoolEntry triggers an IllegalStateException, thereby preventing double release scenarios that could lead to pool corruption. This approach improved the correctness of the pool’s lifecycle, especially under multi-threaded conditions, and reduced the risk of production issues for downstream clients. The work focused on HTTP client functionality and emphasized robust unit testing practices to ensure stability and maintainability in concurrent usage environments.