There is an unifficial Groovy plugin available:
However it has not received a fresh release in a ~year, and there are some pending open issues. Officialifying this plugin, like the CSS plugin, would be great. The Groovy plugin should be kept up-to-date according to the Java rules for the most part (like rule categorizes). An official plugin would be greatly appriciated for this.
Are there any such plans?
Thanks for the answer!