Worked on the apache/celeborn repository to enhance multi-tenant identity resolution by addressing a bug in the DefaultIdentityProvider. Focused on backend development and configuration management, the solution ensured that tenant IDs and usernames are now sourced directly from user-provided values in CelebornConf, rather than defaulting incorrectly. This approach improved the reliability of tenant isolation and reduced the risk of misconfiguration in production environments. The work involved unit testing to validate the changes and was implemented using Java and Scala. By aligning runtime behavior with explicit configuration, the update strengthened correctness and maintainability in multi-tenant deployments for Celeborn.