Configure Custom Gradle Plugin Extension with ${buildDir}

How do I configure a default gradle plugin extension property with $buildDir? e.g. ${buildDir}/ as default

I don’t understand the question. Can you please elaborate.

for example

class MyExtension {

def myDir = new File(buildDir, ‘myFolder’)


where buildDir is -> a link to project build directory / build build.gradle

How to do that ?