Comment by brabel

Groovy closure delegates' type can be declared, giving as much information as with Kotlin. The reason you couldn't follow the code was that the people who wrote those things either didn't declare types, or IntelliJ wasn't using the type declarations (I believe Groovy support in Gradle files is less good than in general Groovy files, where the IDE does support this). You're correct that some plugins will resolve things dynamically and those cannot be resolved by the IDE. But that's not the fault of the language, if you're going to rewrite in Kotlin with types, you could just as well add types to your Groovy declarations for the same result.