According to the list of supported languages for syntax highlighting, Groovy has been missing for many years, despite the fact that highlight.js supports Groovy and Groovy is not a particularly exotic language. Far more exotic ones like Haskell, Erlang, Ocaml etc. are supported, but not a widely used JVM language like Groovy. Using ```java as a replacement for Groovy is just a crutch or a suboptimal workaround, as discussed here previously.
Groovy is used as a stand-alone programming language for projects like Grails, Gradle, Spock, Geb and many more, as a scripting language for Jenkins, Jira and - again - Gradle (each Gradle build file is Groovy code). The list could go on endlessly. It would be a minor effort to support lang-groovy and connect important tags like groovy to that language syntax highlighter. The benefit would be huge to a big developer community active on Stack Overflow.
