Debugging a Gradle plugin in IntelliJ IDEA

How can I debug a Gradle plugin in IntelliJ IDEA? (current version 2019.3.1)

I want to create a breakpoint in plugin code and debug it as it's running.

Is there any built-in Gradle or IntelliJ support for this? Or any useful plugin for either?

Is creating a composite build that has `includeBuild("path to plugin project")` in its `settings.gradle.kts` the best way? If so, must the composite build be the root of the IntelliJ project? Or can I have the plugin code be the root, and the composite just a file in the project, and still somehow debug the composite from IntelliJ?

Thanks.