How to add/set icon to Arc.UserDialogs ActionSheet?

I am using Arc.UserDialogs ActionSheet in my xamarin form app. But I am unable to attach a icons to the action sheet items. It asks a string value. I set image name but not working.

 UserDialogs.Instance.ActionSheet(new ActionSheetConfig()
                            .SetTitle("Choose Type")
                            .Add("Default", null, "icon1.png")
                            .Add("E-Mail", null, "icon2.png")
                        );