Mimmic FXML in Kotlin using only one extention method

JavaFXBuilder.kt

fun main(args:Array<String>){
    Application.launch(javaClass<Foo>())
}

fun <T:Any> T.builder(f:T.()->Unit):T{
    this.f()
    return this
}

class Foo : Application(){
    override fun start(primaryStage: Stage) {
        val s=Scene(AnchorPane().builder {
            this.getChildren().addAll(
                    TextField("e").builder {
                        AnchorPane.setLeftAnchor(this,0.toDouble())
                        AnchorPane.setRightAnchor(this,200.toDouble())
                        setPrefWidth(300.toDouble())
                    },
                    Button().builder {
                        AnchorPane.setRightAnchor(this,0.toDouble())
                        setPrefWidth(200.toDouble())
                    }
            )
        })
        primaryStage.setScene(s)
        primaryStage.show()
    }

}

You builder function seem to be the same as the library function with