How to read the Gradle implementation classes source code directly in IntelliJ idea?

I would like to read the source code of various Gradle implementation classes in the IntelliJ IDEA. However, I always get only the Interface (e.g. or

I would rather like to view the classes implementing Project and Task which are used by Gradle. I would like to see how things are implemented.

How do I quickly show those implementing classes in IDEA?

You can always checkout gradle code from github, run ./gradlew idea and import the generated project into the IDE. You can then open the interface (like Project for example) and IntelliJ will list all implementing classes.