Custom Gradle plugin doLast() in task

Question

I am writing a custom Gradle plugin and trying to figure out how can I call a doLast() function inside my Gradle plugin then supplying some logic in there, but unfortunately with not much success.

This is syntax error at it.delete( Unresolved reference: delete:

project.tasks.create("cleanMendix", Delete::class.java) {task ->
    task.doLast{
        it.delete(
            "${project.projectDir}/target",
            "${project.projectDir}/.mendix-cache",
            "${project.projectDir}/userlib",
            "${project.projectDir}/deployment"
        )
    }
}.apply {
    group = "mendix"
}

This is not deleting the files:

        project.tasks.create("cleanMendix", Delete::class.java) {task ->
        task.doLast{
            task.delete(
                "${project.projectDir}/target",
                "${project.projectDir}/.mendix-cache",
                "${project.projectDir}/userlib",
                "${project.projectDir}/deployment"
            )
        }
    }.apply {
        group = "mendix"
    }

If I call without doLast() it's working but it is also run in the configuration phase.