Worked on the square/okhttp repository to improve the reliability of TLS handshake testing across platforms. Addressed a persistent issue with flaky Handshake Certificates tests by expanding the Major Issuer List, ensuring that additional recognized certificate authorities are correctly validated. This change reduced intermittent CI failures and enhanced the accuracy of cross-platform certificate issuer verification. The work involved careful maintenance of test data and a strong understanding of TLS security practices. Utilized Kotlin for both development and testing, focusing on software quality and stability. The contribution improved the OkHttp test suite’s reliability, supporting faster feedback cycles and more confident releases.