Are you sure there is no output? The dark theme in GroovyConsole isn't very good, the output font color is almost (if not) the same as the background color making it impossible to read.

I use Ubuntu in dark mode and I have this script for starting groovyConsole in light mode

#!/usr/bin/env bash
# groovyConsole color theme and Ubuntu dark theme is not a good match...
Exec=env GTK_THEME=adwaita:light ~/.sdkman/candidates/groovy/current/bin/groovyConsole