Set initially selected item index/id in BottomNavigationView

[QiiqeAzuara]

since Android Support Library v25.3.0 new method was added:
bottomNavigationView.setSelectedItemId(R.id.item_id);

In ViewSwapper exist an method:
public void showItemAt(int position) {}

both return NullPointerException :(
Log:
Caused by: java.lang.NullPointerException: Attempt to read from field 'int android.support.v4.app.Fragment.mIndex' on a null object reference