How to bind multiple field in the group header?

<ContentPage xmlns:syncfusion="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms">
 
  <ContentPage.Resources>
        <ResourceDictionary>
            <local:GroupHeaderConverter x:Key="TemplateConverter"/>
            <local:BoolToImageConverter x:Key="BoolToImageConverter"/>
        </ResourceDictionary>
    </ContentPage.Resources>
 
  <ContentPage.Content>
        <Grid >
            <syncfusion:SfListView x:Name="listView" ItemSize="80" 
                                   SelectionMode="Single"
                                   AllowGroupExpandCollapse="True"
                                   GroupHeaderSize="60"
                                   ItemsSource="{Binding EmployeeInfo}"                                   
                                   ItemSpacing="2">
                <syncfusion:SfListView.GroupHeaderTemplate>
                    <DataTemplate>
                        <ViewCell>
                            <ViewCell.View>
                                <Grid>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="50"/>
                                        <ColumnDefinition Width="*"/>
                                        <ColumnDefinition Width="30"/>
                                    </Grid.ColumnDefinitions>
 
                                    <Image x:Name="groupimage" Grid.Column="0"                
                                           Source="{Binding .,Converter={StaticResource TemplateConverter}, ConverterParameter={x:Reference Name=groupimage}}"/>
                                    <Grid Grid.Column="1">
                                        <Grid.RowDefinitions>
                                            <RowDefinition Height="*"/>
                                            <RowDefinition Height="20"/>
                                        </Grid.RowDefinitions>
                                        <Label x:Name="grouplabel" Grid.Row="0" 
                                              Text="{Binding .,Converter={StaticResource TemplateConverter}, ConverterParameter={x:Reference Name=grouplabel}}"/>
                                        <ProgressBar Grid.Row="1" Progress=".2" />
                                    </Grid>
                                    <Image x:Name="NormalImage" Grid.Column="2"                                                               
                                           Source="{Binding IsExpand, Converter={StaticResource BoolToImageConverter}}"/>
                                </Grid>
                            </ViewCell.View>
                        </ViewCell>
                    </DataTemplate>
                </syncfusion:SfListView.GroupHeaderTemplate>
            </syncfusion:SfListView>
        </Grid>
    </ContentPage.Content>
</ContentPage>

public class GroupHeaderConverter : IValueConverter
{
   public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
   {
      if (value == null)
         return null;
 
 var groupdataitems = (value as GroupResult).Items.ToList<Employee>().ToList();
 var data = groupdataitems[0];
       if (parameter is Label)
    return data.GroupingData.Designation;
       else
    return data.GroupingData.EmployeeImage;
   }
}