I don't think there is any real dependency here. If anyone want to take a shot at this, please do.
We have actually talked about migrating the Ant build to Gradle build in GitHub issue #743 about 2 years ago. Fortunately (or unfortunately) we managed to solve the issue at hand at the time. So, we/I didn't actually look into it afterward. Now, if I would have time to do that, I would probably migrate the build system to Gradle + migrate the Java code (that we maintain) to Kotlin. Once you have tasted them, it hard to go back to the old ways!