Nullable refernce types refactoring

WotBlitzStatisticsPro.DataAccess/Model/AchievementSectionDictionary.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Linq;
 using MongoDB.Bson.Serialization.Attributes;
 using WotBlitzStatisticsPro.Common.Dictionaries;
 
@@ -6,9 +7,10 @@ namespace WotBlitzStatisticsPro.DataAccess.Model
 {
     public class AchievementSectionDictionary: IAchievementSectionDictionary
     {
-        [BsonId]
-        public string AchievementSectionId { get; set; }
+        [BsonId] public string AchievementSectionId { get; set; } = string.Empty;
         public int Order { get; set; }
-        public List<LocalizableString> AchievementSectionNames { get; set; }
+
+        public List<LocalizableString> AchievementSectionNames { get; set; } =
+            Enumerable.Empty<LocalizableString>().ToList();
     }
 }