Gradle for Android, Groovy on Android and Grails 3 Testing.
Great video links, Gradle tips to improve your Android projects, Grails async and Groovy tips.
How to profile Groovy and measure performance, Ratpack intro and how to secure Grails 3 apps
Learn how to create functional tests with Geb, AST Transformations and yes; microservices.
Both of them, Gradle and Spock, are great Trojan horses to spread Groovy's adoption.