public NullableDateTimeOffsetToRelativeDateTimeStringValueConverter(
     NSRelativeDateTimeFormatterStyle dateTimeStyle,
     NSRelativeDateTimeFormatterUnitsStyle unitsStyle
     )
 {
     _converter = new DateTimeOffsetToRelativeDateTimeStringValueConverter(dateTimeStyle, unitsStyle);
 }
 public NullableDateTimeOffsetToRelativeDateTimeStringValueConverter()
 {
     _converter = new DateTimeOffsetToRelativeDateTimeStringValueConverter(DefaultDateTimeStyle, DefaultUnitsStyle);
 }