There is now a Gradle Plugin to help Gradle developers produce Maven plugins.

https://github.com/britter/maven-plugin-development

If there's a desire to unify the build, this may help by allowing us to simplify the plugin development for this project: https://github.com/diffplug/spotless/tree/master/plugin-maven