Merge pull request #2767 from Bond-009/nullable3

Enable nullabe reference types for MediaBrowser.Model

MediaBrowser.Controller/LiveTv/TimerEventInfo.cs

@@ -1,10 +1,19 @@
+#nullable enable
+#pragma warning disable CS1591
+
 using System;
 
 namespace MediaBrowser.Controller.LiveTv
 {
     public class TimerEventInfo
     {
-        public string Id { get; set; }
-        public Guid ProgramId { get; set; }
+        public TimerEventInfo(string id)
+        {
+            Id = id;
+        }
+
+        public string Id { get; }
+
+        public Guid? ProgramId { get; set; }
     }
 }