Final Results

Your RosterListFragment should look like:

package com.commonsware.todo

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment

class RosterListFragment : Fragment() {
  override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
  ): View? {
    return inflater.inflate(R.layout.todo_roster, container, false)
  }
}

(from T07-Fragments/ToDo/app/src/main/java/com/commonsware/todo/RosterListFragment.kt)