Because Kotlin is the language being financially supported by a business, perhaps it's better to ask for an example where Groovy is more compatible than Kotlin. The only example I can think of is scripting in Grails. Even Grails 3, which was released over 2 years ago at the same time VMware ended its paid support for Groovy, only uses Groovy for its scripting.

I think it would be hard to call dynamic groovy types from java