private static bool IsValidAndFilter(AndFilter andFilter, ref ExDateTime?start, ref ExDateTime?end)
 {
     if (andFilter == null)
     {
         return(false);
     }
     foreach (QueryFilter queryFilter in andFilter.Filters)
     {
         if (!CalendarViewParameters.IsValidFilter(queryFilter, ref start, ref end))
         {
             return(false);
         }
     }
     return(true);
 }
 private static bool IsValidFilter(QueryFilter queryFilter, ref ExDateTime?start, ref ExDateTime?end)
 {
     return(CalendarViewParameters.IsValidComparisonFilter(queryFilter as ComparisonFilter, ref start, ref end) || CalendarViewParameters.IsValidAndFilter(queryFilter as AndFilter, ref start, ref end));
 }