Kotlin delegation for gradle task

I have something like this:

interface Base {
    var a: String?
    var b: String?

class BaseImpl(override var a: String?, override var b: String?) : Base{

Now I have to get the value of a and b using kotlin delegation in gradle task.
I am testing this use case passing the parameter a = “something”
but I don’t know how to get this value of ‘a’ which I passed through test.
This is the class of gradle task in which I have to get this values.

class A : DefaultTask(), Base by BaseImpl()

fun doSomething {