Worked on targeted maintenance for the apache/jena repository, focusing on improving developer experience and error clarity within the Java codebase. Addressed two key bugs by clarifying Jena Core API documentation and refining error message formatting for language tag processing. Applied API refactoring and enhanced error handling to reduce deprecation warnings, updating Javadoc references to direct developers toward the correct RIOT API class. Improved the accuracy of error reporting by correcting format string issues, ensuring invalid language tag characters are clearly displayed. These updates contributed to smoother downstream integration and easier maintenance, demonstrating attention to detail in Java development and bug fixing.