title: Material Button Toggle Group single selection
body: <p>How can I force a <strong>MaterialButtonToggleGroup</strong> to act like a RadioGroup as in having at least one selected item always? Setting <code>setSingleSelection(true)</code> also adds the possibility to have nothing selected if you click twice on a Button in the group.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>&lt;com.google.android.material.button.MaterialButtonToggleGroup
              android:id="@id/BottomSheetDialog_fromFragmentBottomSheetSort_Sort_ToggleButtonGroup"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              app:singleSelection="true"
              app:checkedButton="@+id/BottomSheetDialog_fromFragmentBottomSheetSort_Sort_ToggleButtonGroup_Ascending"&gt;
  
          &lt;com.google.android.material.button.MaterialButton
                  android:id="@id/BottomSheetDialog_fromFragmentBottomSheetSort_Sort_ToggleButtonGroup_Ascending"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:text="@string/Fragment_BottomSheetDialog_Sort_ToggleButton_Ascending"
                  app:backgroundTint="@color/custom_button_background_states"
                  style="@style/Widget.MaterialComponents.Button.OutlinedButton"/&gt;
  
          &lt;com.google.android.material.button.MaterialButton
                  android:id="@id/BottomSheetDialog_fromFragmentBottomSheetSort_Sort_ToggleButtonGroup_Descending"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:text="@string/Fragment_BottomSheetDialog_Sort_ToggleButton_Descending"
                  app:backgroundTint="@color/custom_button_background_states"
                  style="@style/Widget.MaterialComponents.Button.OutlinedButton"/&gt;
      &lt;/com.google.android.material.button.MaterialButtonToggleGroup&gt;
  </code></pre>
  
  <p>As you can see, even while using <strong>app:singleSelection="true"</strong> if i click on an already checked button, it unchecks it leaving no button checked in the group.</p>