Groovy custom annotations are versatile. See 10 tested examples covering annotation declaration, retention policies, AST transformations, and runtime processing. “Annotations are metadata that give your code a voice – they tell the compiler, the runtime, and other developers what your intentions are without cluttering your logic.” Joshua Bloch, Effective Java Last Updated: March 2026 | Tested on: Groovy 4.x / 5.x, Java 11+ | Difficulty: Advanced | Reading Time: 18 minutes Groovy ships with a rich set of built-in annotations ... Read More