Spring Framework 7 and Spring Boot 4 Deliver API Versioning, Resilience, and Null-Safe Annotations

Spring Framework 7.0 and Spring Boot 4.0 introduce first-class REST API versioning with multiple strategies (path, header, query, media type), standardized null safety through JSpecify annotations, and built-in resilience features like retry and concurrency throttling. The releases migrate to Jackson 3 for JSON processing, modularize Spring Boot's autoconfiguration into technology-specific modules, and maintain JDK 17 baseline while supporting JDK 25. New baselines include Jakarta EE 11 and Kotlin 2.2. Additional improvements include HTTP Interface Groups, multi-factor authentication in Spring Security 7, GraalVM Native Image optimizations, and coordinated releases across the Spring ecosystem.