Remove separator beneath ListView GroupHeaderTemplate?

Is there any way to remove the separator beneath the ListView group headers?

I'm not doing anything special in the DataTemplate.

  <ListView.GroupHeaderTemplate>
    <DataTemplate>
      <ViewCell 
        Height="45">
        <StackLayout
          BackgroundColor="White"
          VerticalOptions="FillAndExpand"
          HorizontalOptions="FillAndExpand">
          <StackLayout
            VerticalOptions="CenterAndExpand"
            Margin="15, 0, 5, 0">
            <Label
              Text="{Binding LongName}" />
          </StackLayout>
        </StackLayout>
      </ViewCell>
    </DataTemplate>
  </ListView.GroupHeaderTemplate>