1 files changed, 17 insertions, 14 deletions

diff --git a/MediaBrowser.Controller/Entities/Folder.cs b/MediaBrowser.Controller/Entities/Folder.cs
index 83c19a54e..1bec66f95 100644
--- a/MediaBrowser.Controller/Entities/Folder.cs
+++ b/MediaBrowser.Controller/Entities/Folder.cs
@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.IO;
 using System.Linq;
 using System.Security;
@@ -11,6 +12,7 @@ using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Dataflow;
+using J2N.Collections.Generic.Extensions;
 using Jellyfin.Data.Entities;
 using Jellyfin.Data.Enums;
 using Jellyfin.Extensions;
@@ -247,7 +249,7 @@ namespace MediaBrowser.Controller.Entities
         /// We want this synchronous.
         /// </summary>
         /// <returns>Returns children.</returns>
-        protected virtual List<BaseItem> LoadChildren()
+        protected virtual IReadOnlyList<BaseItem> LoadChildren()
         {
             // logger.LogDebug("Loading children from {0} {1} {2}", GetType().Name, Id, Path);
             // just load our children from the repo - the library will be validated and maintained in other processes
@@ -659,7 +661,7 @@ namespace MediaBrowser.Controller.Entities
         /// Get our children from the repo - stubbed for now.
         /// </summary>
         /// <returns>IEnumerable{BaseItem}.</returns>
-        protected List<BaseItem> GetCachedChildren()
+        protected IReadOnlyList<BaseItem> GetCachedChildren()
         {
             return ItemRepository.GetItemList(new InternalItemsQuery
             {
@@ -1283,14 +1285,14 @@ namespace MediaBrowser.Controller.Entities
             return true;
         }
 
-        public List<BaseItem> GetChildren(User user, bool includeLinkedChildren)
+        public IReadOnlyList<BaseItem> GetChildren(User user, bool includeLinkedChildren)
         {
             ArgumentNullException.ThrowIfNull(user);
 
             return GetChildren(user, includeLinkedChildren, new InternalItemsQuery(user));
         }
 
-        public virtual List<BaseItem> GetChildren(User user, bool includeLinkedChildren, InternalItemsQuery query)
+        public virtual IReadOnlyList<BaseItem> GetChildren(User user, bool includeLinkedChildren, InternalItemsQuery query)
         {
             ArgumentNullException.ThrowIfNull(user);
 
@@ -1304,7 +1306,7 @@ namespace MediaBrowser.Controller.Entities
 
             AddChildren(user, includeLinkedChildren, result, false, query);
 
-            return result.Values.ToList();
+            return result.Values.ToImmutableList();
         }
 
         protected virtual IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
@@ -1369,7 +1371,7 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        public virtual IEnumerable<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
+        public virtual IReadOnlyList<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
         {
             ArgumentNullException.ThrowIfNull(user);
 
@@ -1377,35 +1379,35 @@ namespace MediaBrowser.Controller.Entities
 
             AddChildren(user, true, result, true, query);
 
-            return result.Values;
+            return result.Values.ToImmutableList();
         }
 
         /// <summary>
         /// Gets the recursive children.
         /// </summary>
         /// <returns>IList{BaseItem}.</returns>
-        public IList<BaseItem> GetRecursiveChildren()
+        public IReadOnlyList<BaseItem> GetRecursiveChildren()
         {
             return GetRecursiveChildren(true);
         }
 
-        public IList<BaseItem> GetRecursiveChildren(bool includeLinkedChildren)
+        public IReadOnlyList<BaseItem> GetRecursiveChildren(bool includeLinkedChildren)
         {
             return GetRecursiveChildren(i => true, includeLinkedChildren);
         }
 
-        public IList<BaseItem> GetRecursiveChildren(Func<BaseItem, bool> filter)
+        public IReadOnlyList<BaseItem> GetRecursiveChildren(Func<BaseItem, bool> filter)
         {
             return GetRecursiveChildren(filter, true);
         }
 
-        public IList<BaseItem> GetRecursiveChildren(Func<BaseItem, bool> filter, bool includeLinkedChildren)
+        public IReadOnlyList<BaseItem> GetRecursiveChildren(Func<BaseItem, bool> filter, bool includeLinkedChildren)
         {
             var result = new Dictionary<Guid, BaseItem>();
 
             AddChildrenToList(result, includeLinkedChildren, true, filter);
 
-            return result.Values.ToList();
+            return result.Values.ToImmutableList();
         }
 
         /// <summary>
@@ -1556,11 +1558,12 @@ namespace MediaBrowser.Controller.Entities
         /// Gets the linked children.
         /// </summary>
         /// <returns>IEnumerable{BaseItem}.</returns>
-        public IEnumerable<Tuple<LinkedChild, BaseItem>> GetLinkedChildrenInfos()
+        public IReadOnlyList<Tuple<LinkedChild, BaseItem>> GetLinkedChildrenInfos()
         {
             return LinkedChildren
                 .Select(i => new Tuple<LinkedChild, BaseItem>(i, GetLinkedChild(i)))
-                .Where(i => i.Item2 is not null);
+                .Where(i => i.Item2 is not null)
+                .ToImmutableList();
         }
 
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, IReadOnlyList<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)