Can't set a default checked Button

[jokerstudios]

Hey,
thank you for your great library.
I have a problem with the Radio Group.
I cant see or use the checkedPosition or checkedButton method.
They just dont show up?

private RadioRealButtonGroup radioRealButtonGroup
radioRealButtonGroup = findViewById(R.id.real_readio_button_category);

And these to methods are just red and not found ( I know that checkedButton needs a reference, just for demo purpose no one included here)
radioRealButtonGroup.checkedPosition(2);
radioRealButtonGroup.checkedButton();

[Ayo]

radioRealButtonGroup.setPosition(n); make the trick