Worked on the apache/iceberg repository to address a security-critical issue in backend credential management. Focused on Java-based backend development, this work involved fixing a bug where storage credentials were not properly propagated when creating FileIO instances with a custom ioBuilder. The solution aligned the ioBuilder path with the reflection path, ensuring consistent and secure credential handling across different IO creation methods. Comprehensive unit and end-to-end tests were added to verify that credentials are correctly set, reducing integration risks for external systems such as Trino. This targeted fix improved both the security and reliability of FileIO credential propagation mechanisms.