In Jan 2026, delivered notable features and fixes across two repositories, with a focus on Jackson 3 migration readiness, documentation alignment, and test reliability. Key work included: 1) JSON API Compatibility Update (Jackson 3) in spring-kafka: updated docs to replace deprecated JSON serialization/deserialization APIs with Jackson 3 counterparts, and adjusted examples for Jackson 3 usage; commits fixed references to deprecated serde APIs and updated guidance for JsonMapper usage. Commit: b8b9be0b123b5d8872744efa823397ed5007478b. 2) Spring Kafka 4.0 migration with Jackson 3 serialization support in rewrite-spring: added Jackson 3 migration recipes, regenerated type tables, and migrated tooling/docs to support Spring Kafka 4.0 migration with Jackson 3; commits: a33637b63fe26ad80cc72e4f869895dcced9f57d and df78d34c72d0d3d56e7799aee3c011567a6a8965. 3) Test infrastructure improvement: AutoConfigureTestRestTemplate to align with Spring Boot 4.x changes, preventing test configuration issues in Boot 4.x environments; commit: 54d8115c0656668c2d52740f4c94364f209cb3d8. Overall impact: enabled a smoother upgrade path for users migrating to Jackson 3 and Spring Kafka 4.0, improved documentation and migration tooling, and strengthened test reliability in Boot 4.x projects. Technologies/skills demonstrated: Jackson 3 migration, Spring Kafka 4.0 readiness, migration recipe development, test infrastructure alignment, and documentation updates.

June 2025 monthly summary for spring-framework focused on documentation accuracy for ModelAttribute handling in Spring MVC. Corrected the documented exception type from MethodArgumentNotValueException to MethodArgumentNotValidException to reflect the actual runtime behavior. Implemented in the spring-framework repo with a single commit that updates the docs and aligns API references with code. The change enhances developer experience by reducing confusion, potential misuse, and support friction, and supports smoother onboarding for new contributors and users.