Groovy Calamari is a curated publication full of interesting, relevant links about Microservices, Micronaut and Groovy Ecosystem (Grails, Gradle, ...). Curated by Sergio del Amo and published weekly. Free.
If you have been subscribed to this newsletter for a while, you know Geb is among my favorites projects in the Groovy ecosystem. I was lucky enough to interview Marcin Erdmann, Geb Project lead in the latest podcast episode.
I have been writing Java and Groovy applications for years whiteout writing an Annotation. However, annotations are powerful feature of Java and this introduction by @baeldung on how to create custom annotations, and how to process them will give you a head start.