Its not really a plugin for UE but just a config in your tools menu. See groovy site for more details

http://groovy.codehaus.org/UltraEdit+Plugin

Using another software I stumbled about "Groovy". I want to ask about the current state of Groovy usage in UE 24.10.0.35?

Help files contains no info, the old posting from 2006 above links to a dead page.

Peter, I suppose the Groovy plugin for UltraEdit was mainly a syntax highlighting wordfile for Groovy as it can be downloaded from User-submitted wordfiles for UltraEdit/UEStudio and an instruction for configuration of one or more user tools to execute active Groovy file.

Thanks Mofi

but - maybe I understand it completely wrong - I would like to know: UE supports JS (not only in writing, but in executing) inside UE. Does UE also supports "Groovy - JS" as scripting inside UE?

UltraEdit has built-in the JavaScript core library making it possible to execute JavaScript code using only JavaScript core objects and the UltraEdit/UEStudio specific extensions.

The Groovy programming language is based on Java and not on JavaScript. Do not confuse Java with JavaScript. The two programming languages have very different syntax, semantics, and uses. UltraEdit can definitely not interpret Java or Groovy code.