Worked on the spring-boot repository to address a critical issue with XML serialization of ProblemDetail objects, focusing on backend reliability and data consistency. The solution involved correcting the mixin configuration for Jackson’s XmlMapper by replacing the JSON-specific mixin with the appropriate XML variant, ensuring accurate XML output. Java and the Spring Framework were used to implement and validate the fix, with comprehensive updates to the test suite to confirm correct behavior across serialization formats. This work improved API consistency and prevented format-specific serialization errors, demonstrating careful attention to cross-format compatibility and robust backend development practices within the project.