Mark classes and interfaces using EXRULE as obsolete

Ical.Net/CalendarComponents/IRecurrable.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+using System;
 using System.Collections.Generic;
 using Ical.Net.DataTypes;
 using Ical.Net.Evaluation;
@@ -17,7 +18,10 @@ public interface IRecurrable : IGetOccurrences
     CalDateTime? Start { get; set; }
 
     ExceptionDates ExceptionDates { get; }
+
+    [Obsolete("EXRULE is marked as deprecated in RFC 5545 and will be removed in a future version")]
     IList<RecurrencePattern> ExceptionRules { get; set; }
+
     RecurrenceDates RecurrenceDates { get; }
     IList<RecurrencePattern> RecurrenceRules { get; set; }
     CalDateTime? RecurrenceId { get; set; }

Ical.Net/CalendarComponents/RecurringComponent.cs

@@ -80,6 +80,7 @@ internal IList<PeriodList> ExceptionDatesPeriodLists
 
     public virtual ExceptionDates ExceptionDates { get; internal set; } = null!;
 
+    [Obsolete("EXRULE is marked as deprecated in RFC 5545 and will be removed in a future version")]
     public virtual IList<RecurrencePattern> ExceptionRules
     {
         get => Properties.GetMany<RecurrencePattern>("EXRULE");

Ical.Net/Evaluation/RecurrencePatternEvaluator.cs

@@ -618,7 +618,6 @@ private static IEnumerable<CalDateTime> GetAbsWeekDaysWeekly(CalDateTime date, R
 
         //When we manage weekly recurring pattern and we have boundary case:
         //Weekdays: Dec 31, Jan 1, Feb 1, Mar 1, Apr 1, May 1, June 1, Dec 31 - It's the 53th week of the year, but all another are 1st week number.
-        //So we need an EXRULE for this situation, but only for weekly events
         while (currentWeekNo == weekNo || (nextWeekNo < weekNo && currentWeekNo == nextWeekNo && pattern.Frequency == FrequencyType.Weekly))
         {
             if ((byWeekNoNormalized.Count == 0 || byWeekNoNormalized.Contains(currentWeekNo))

Ical.Net/Evaluation/RecurringEvaluator.cs

@@ -60,6 +60,7 @@
     /// </summary>
     /// <param name="referenceDate"></param>
     /// <param name="options"></param>
+    [Obsolete("EXRULE is marked as deprecated in RFC 5545 and will be removed in a future version")]
     private IEnumerable<Period> EvaluateExRule(CalDateTime referenceDate, EvaluationOptions? options)
     {
         if (!Recurrable.ExceptionRules.Any())
@@ -119,7 +120,7 @@
             periods = periods.Where(p => (p.StartTime >= periodStart) || (p.EffectiveEndTime > periodStart));
         }
 
         var exRuleExclusions = EvaluateExRule(referenceDate, options);
 
         // EXDATEs could contain date-only entries while DTSTART is date-time. This case isn't clearly defined
         // by the RFC, but it seems to be used in the wild (see https://github.com/ical-org/ical.net/issues/829).

Ical.Net/VTimeZoneInfo.cs

@@ -110,6 +110,7 @@ internal IList<PeriodList> ExceptionDatesPeriodLists
 
     public virtual ExceptionDates ExceptionDates { get; private set; } = null!;
 
+    [Obsolete("EXRULE is marked as deprecated in RFC 5545 and will be removed in a future version")]
     public virtual IList<RecurrencePattern> ExceptionRules
     {
         get => Properties.GetMany<RecurrencePattern>("EXRULE");