Java Migration Skill Step-by-step guide for upgrading Java projects between major versions. When to Use - User says "upgrade to Java 25" / "migrate from Java 8" / "update Java version" - Modernizing legacy projects - Spring Boot 2.x → 3.x → 4.x migration - Preparing for LTS version adoption Migration Paths --- Quick Reference: What Breaks | From → To | Major Breaking Changes | |-----------|------------------------| | 8 → 11 | Removed , module system, internal APIs | | 11 → 17 | Sealed classes (preview→final), strong encapsulation | | 17 → 21 | Pattern matching changes, deprecated for removal…