Apache Groovy's original use case was for scripting classes already written in Java, for stuff like testing and glue code. It added closures to Beanshell, which

Apache Groovy's original use case was for scripting classes already written in Java, for stuff like testing and glue code. It added closures to Beanshell, which was the de facto language for scripting Java at the time. New leadership, er, took over in late 2005 and re-oriented it as a DSL for Grails, and later Gradle. Grails has since died, with virtually no-one upgrading to version 3, or starting new projects in it. The Grails 2 plugin scene is dead. Many sites are converting their Gradle build scripts to Basel, so it's also starting a slow decline. Around 2012, Groovy was repurposed again with static typing to compete with Java and Scala on Android. But it never succeeded, and the leadership was retrenched 3 yrs ago from VMWare and couldn't find anyone else to financially support them. Groovy remains OK for scripting Java classes, but it's fast becoming irrelevant now that Java itself has lambdas and type inference.