spring-boot-4-migration-skill

Guides Spring Boot version migrations: 2.7.x to 3.5.x, 3.5.x to 4.x, and minor upgrades within 4.x. Covers Java/Kotlin baseline upgrades, Jakarta EE namespace (javax to jakarta), Hibernate 5/6/7, Spring Security 5/6/7, modular starters, Jackson 3, Spring Framework 7, observability (Micrometer Tracing, OpenTelemetry), property and package relocations, JUnit 6, Testcontainers 2, MockitoBean, HTTP clients, resilience, AOT/native, API versioning, and OpenRewrite recipe automation. Supports all-at-once and gradual strategies with compatibility bridges. Java and Kotlin; Maven and Gradle. Trigger on requests like "upgrade/migrate to Spring Boot 3 or 4", "Spring Boot 2 to 3", "javax to jakarta", "upgrade to 4.1", "OpenRewrite Spring Boot", or any request moving a Spring Boot project to a newer major or minor version. Do NOT use for general Spring Boot development on a fixed version (new endpoints, services, JPA, tests) — use the spring-boot skill for that.