Worked on strengthening the delegation token mechanism in the apache/hadoop repository by addressing a potential NullPointerException within the YARN resource manager. Focused on backend development using Java, the work involved implementing robust error handling through targeted null checks for localServiceAddress and its associated InetAddress. This approach ensured that missing or incomplete data would not cause system crashes, thereby improving the reliability of token-based authentication in production Hadoop clusters. The solution aligned with the requirements of YARN-11776 and contributed to greater operational stability, particularly in multi-tenant environments where resilience and graceful error handling are critical for ongoing cluster operations.