title: How to clear the date bound to a CalendarDatePicker if certain conditions occur in UWP?
body: <p>I have a CalendarDatePicker whose Date property is bound to a converter.
  I don't want it to show the date if the date is default(01-01-0001) </p>
  
  <p>My code</p>
  
  <pre><code>class DateTimeToCalendarDateTimeOffsetConverter : IValueConverter
  {
      public object Convert(object value, Type targetType, object parameter, string language)
      {
          try
          {
              DateTime date = (DateTime)value;
              return new DateTimeOffset(date);
          }
          catch (Exception ex)
          {
              return null;
          }
      }
  
      public object ConvertBack(object value, Type targetType, object parameter, string language)
      {
          try
          {
              DateTimeOffset dto = (DateTimeOffset)value;
              return dto.DateTime;
          }
          catch (Exception ex)
          {
              return DateTime.MinValue;
          }
      }
  }       
  </code></pre>
  
  <p>But by default it set's todays date.
  What value can I set to clear the date?</p>