Merge remote-tracking branch 'upstream/master' into client-logger

MediaBrowser.Controller/Authentication/AuthenticationResult.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using MediaBrowser.Controller.Session;

MediaBrowser.Controller/Authentication/IAuthenticationProvider.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Threading.Tasks;

MediaBrowser.Controller/Authentication/IPasswordResetProvider.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;

MediaBrowser.Controller/BaseItemManager/BaseItemManager.cs

@@ -1,6 +1,8 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
+using Jellyfin.Extensions;
 using MediaBrowser.Controller.Channels;
 using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.Entities;
@@ -13,7 +15,7 @@ namespace MediaBrowser.Controller.BaseItemManager
     {
         private readonly IServerConfigurationManager _serverConfigurationManager;
 
-        private int _metadataRefreshConcurrency = 0;
+        private int _metadataRefreshConcurrency;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="BaseItemManager"/> class.
@@ -50,7 +52,7 @@ namespace MediaBrowser.Controller.BaseItemManager
             var typeOptions = libraryOptions.GetTypeOptions(baseItem.GetType().Name);
             if (typeOptions != null)
             {
-                return typeOptions.MetadataFetchers.Contains(name, StringComparer.OrdinalIgnoreCase);
+                return typeOptions.MetadataFetchers.Contains(name.AsSpan(), StringComparison.OrdinalIgnoreCase);
             }
 
             if (!libraryOptions.EnableInternetProviders)
@@ -60,7 +62,7 @@ namespace MediaBrowser.Controller.BaseItemManager
 
             var itemConfig = _serverConfigurationManager.Configuration.MetadataOptions.FirstOrDefault(i => string.Equals(i.ItemType, GetType().Name, StringComparison.OrdinalIgnoreCase));
 
-            return itemConfig == null || !itemConfig.DisabledMetadataFetchers.Contains(name, StringComparer.OrdinalIgnoreCase);
+            return itemConfig == null || !itemConfig.DisabledMetadataFetchers.Contains(name.AsSpan(), StringComparison.OrdinalIgnoreCase);
         }
 
         /// <inheritdoc />
@@ -81,7 +83,7 @@ namespace MediaBrowser.Controller.BaseItemManager
             var typeOptions = libraryOptions.GetTypeOptions(baseItem.GetType().Name);
             if (typeOptions != null)
             {
-                return typeOptions.ImageFetchers.Contains(name, StringComparer.OrdinalIgnoreCase);
+                return typeOptions.ImageFetchers.Contains(name.AsSpan(), StringComparison.OrdinalIgnoreCase);
             }
 
             if (!libraryOptions.EnableInternetProviders)
@@ -91,14 +93,14 @@ namespace MediaBrowser.Controller.BaseItemManager
 
             var itemConfig = _serverConfigurationManager.Configuration.MetadataOptions.FirstOrDefault(i => string.Equals(i.ItemType, GetType().Name, StringComparison.OrdinalIgnoreCase));
 
-            return itemConfig == null || !itemConfig.DisabledImageFetchers.Contains(name, StringComparer.OrdinalIgnoreCase);
+            return itemConfig == null || !itemConfig.DisabledImageFetchers.Contains(name.AsSpan(), StringComparison.OrdinalIgnoreCase);
         }
 
         /// <summary>
         /// Called when the configuration is updated.
         /// It will refresh the metadata throttler if the relevant config changed.
         /// </summary>
-        private void OnConfigurationUpdated(object sender, EventArgs e)
+        private void OnConfigurationUpdated(object? sender, EventArgs e)
         {
             int newMetadataRefreshConcurrency = GetMetadataRefreshConcurrency();
             if (_metadataRefreshConcurrency != newMetadataRefreshConcurrency)
@@ -111,6 +113,7 @@ namespace MediaBrowser.Controller.BaseItemManager
         /// <summary>
         /// Creates the metadata refresh throttler.
         /// </summary>
+        [MemberNotNull(nameof(MetadataRefreshThrottler))]
         private void SetupMetadataThrottler()
         {
             MetadataRefreshThrottler = new SemaphoreSlim(_metadataRefreshConcurrency);

MediaBrowser.Controller/BaseItemManager/IBaseItemManager.cs

@@ -32,4 +32,4 @@ namespace MediaBrowser.Controller.BaseItemManager
         /// <returns><c>true</c> if image fetcher is enabled, else false.</returns>
         bool IsImageFetcherEnabled(BaseItem baseItem, LibraryOptions libraryOptions, string name);
     }
-}
+}

MediaBrowser.Controller/Channels/Channel.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -15,6 +17,12 @@ namespace MediaBrowser.Controller.Channels
 {
     public class Channel : Folder
     {
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        [JsonIgnore]
+        public override SourceType SourceType => SourceType.Channel;
+
         public override bool IsVisible(User user)
         {
             var blockedChannelsPreference = user.GetPreferenceValues<Guid>(PreferenceKind.BlockedChannels);
@@ -37,12 +45,6 @@ namespace MediaBrowser.Controller.Channels
             return base.IsVisible(user);
         }
 
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override SourceType SourceType => SourceType.Channel;
-
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
         {
             try
@@ -82,7 +84,7 @@ namespace MediaBrowser.Controller.Channels
 
         internal static bool IsChannelVisible(BaseItem channelItem, User user)
         {
-            var channel = ChannelManager.GetChannel(channelItem.ChannelId.ToString(""));
+            var channel = ChannelManager.GetChannel(channelItem.ChannelId.ToString(string.Empty));
 
             return channel.IsVisible(user);
         }

MediaBrowser.Controller/Channels/ChannelItemInfo.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA2227, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -11,6 +13,19 @@ namespace MediaBrowser.Controller.Channels
 {
     public class ChannelItemInfo : IHasProviderIds
     {
+        public ChannelItemInfo()
+        {
+            MediaSources = new List<MediaSourceInfo>();
+            TrailerTypes = new List<TrailerType>();
+            Genres = new List<string>();
+            Studios = new List<string>();
+            People = new List<PersonInfo>();
+            Tags = new List<string>();
+            ProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            Artists = new List<string>();
+            AlbumArtists = new List<string>();
+        }
+
         public string Name { get; set; }
 
         public string SeriesName { get; set; }
@@ -78,18 +93,5 @@ namespace MediaBrowser.Controller.Channels
         public bool IsLiveStream { get; set; }
 
         public string Etag { get; set; }
-
-        public ChannelItemInfo()
-        {
-            MediaSources = new List<MediaSourceInfo>();
-            TrailerTypes = new List<TrailerType>();
-            Genres = new List<string>();
-            Studios = new List<string>();
-            People = new List<PersonInfo>();
-            Tags = new List<string>();
-            ProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            Artists = new List<string>();
-            AlbumArtists = new List<string>();
-        }
     }
 }

MediaBrowser.Controller/Channels/ChannelItemResult.cs

@@ -1,18 +1,19 @@
 #pragma warning disable CS1591
 
+using System;
 using System.Collections.Generic;
 
 namespace MediaBrowser.Controller.Channels
 {
     public class ChannelItemResult
     {
-        public List<ChannelItemInfo> Items { get; set; }
-
-        public int? TotalRecordCount { get; set; }
-
         public ChannelItemResult()
         {
-            Items = new List<ChannelItemInfo>();
+            Items = Array.Empty<ChannelItemInfo>();
         }
+
+        public IReadOnlyList<ChannelItemInfo> Items { get; set; }
+
+        public int? TotalRecordCount { get; set; }
     }
 }

MediaBrowser.Controller/Channels/ChannelLatestMediaSearch.cs

@@ -0,0 +1,11 @@
+#nullable disable
+
+#pragma warning disable CS1591
+
+namespace MediaBrowser.Controller.Channels
+{
+    public class ChannelLatestMediaSearch
+    {
+        public string UserId { get; set; }
+    }
+}

MediaBrowser.Controller/Channels/ChannelSearchInfo.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Controller.Channels
@@ -8,9 +10,4 @@ namespace MediaBrowser.Controller.Channels
 
         public string UserId { get; set; }
     }
-
-    public class ChannelLatestMediaSearch
-    {
-        public string UserId { get; set; }
-    }
 }

MediaBrowser.Controller/Channels/IChannel.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Collections.Generic;

MediaBrowser.Controller/Channels/IChannelManager.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -49,32 +51,47 @@ namespace MediaBrowser.Controller.Channels
         /// Gets the channels internal.
         /// </summary>
         /// <param name="query">The query.</param>
+        /// <returns>The channels.</returns>
         QueryResult<Channel> GetChannelsInternal(ChannelQuery query);
 
         /// <summary>
         /// Gets the channels.
         /// </summary>
         /// <param name="query">The query.</param>
+        /// <returns>The channels.</returns>
         QueryResult<BaseItemDto> GetChannels(ChannelQuery query);
 
         /// <summary>
-        /// Gets the latest media.
+        /// Gets the latest channel items.
         /// </summary>
+        /// <param name="query">The item query.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The latest channels.</returns>
         Task<QueryResult<BaseItemDto>> GetLatestChannelItems(InternalItemsQuery query, CancellationToken cancellationToken);
 
         /// <summary>
-        /// Gets the latest media.
+        /// Gets the latest channel items.
         /// </summary>
+        /// <param name="query">The item query.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The latest channels.</returns>
         Task<QueryResult<BaseItem>> GetLatestChannelItemsInternal(InternalItemsQuery query, CancellationToken cancellationToken);
 
         /// <summary>
         /// Gets the channel items.
         /// </summary>
+        /// <param name="query">The query.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The channel items.</returns>
         Task<QueryResult<BaseItemDto>> GetChannelItems(InternalItemsQuery query, CancellationToken cancellationToken);
 
         /// <summary>
-        /// Gets the channel items internal.
+        /// Gets the channel items.
         /// </summary>
+        /// <param name="query">The query.</param>
+        /// <param name="progress">The progress to report to.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The channel items.</returns>
         Task<QueryResult<BaseItem>> GetChannelItemsInternal(InternalItemsQuery query, IProgress<double> progress, CancellationToken cancellationToken);
 
         /// <summary>
@@ -82,9 +99,14 @@ namespace MediaBrowser.Controller.Channels
         /// </summary>
         /// <param name="item">The item.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
-        /// <returns>Task{IEnumerable{MediaSourceInfo}}.</returns>
+        /// <returns>The item media sources.</returns>
         IEnumerable<MediaSourceInfo> GetStaticMediaSources(BaseItem item, CancellationToken cancellationToken);
 
+        /// <summary>
+        /// Whether the item supports media probe.
+        /// </summary>
+        /// <param name="item">The item.</param>
+        /// <returns>Whether media probe should be enabled.</returns>
         bool EnableMediaProbe(BaseItem item);
     }
 }

MediaBrowser.Controller/Channels/IDisableMediaSourceDisplay.cs

@@ -0,0 +1,12 @@
+namespace MediaBrowser.Controller.Channels
+{
+    /// <summary>
+    /// Disable media source display.
+    /// </summary>
+    /// <remarks>
+    /// <see cref="Channel"/> can inherit this interface to disable being displayed.
+    /// </remarks>
+    public interface IDisableMediaSourceDisplay
+    {
+    }
+}

MediaBrowser.Controller/Channels/IHasCacheKey.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Controller.Channels

MediaBrowser.Controller/Channels/IHasFolderAttributes.cs

@@ -0,0 +1,9 @@
+#pragma warning disable CA1819, CS1591
+
+namespace MediaBrowser.Controller.Channels
+{
+    public interface IHasFolderAttributes
+    {
+        string[] Attributes { get; }
+    }
+}

MediaBrowser.Controller/Channels/IRequiresMediaInfoCallback.cs

@@ -1,5 +1,3 @@
-#pragma warning disable CS1591
-
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
@@ -7,11 +5,17 @@ using MediaBrowser.Model.Dto;
 
 namespace MediaBrowser.Controller.Channels
 {
+    /// <summary>
+    /// The channel requires a media info callback.
+    /// </summary>
     public interface IRequiresMediaInfoCallback
     {
         /// <summary>
         /// Gets the channel item media information.
         /// </summary>
+        /// <param name="id">The channel item id.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The enumerable of media source info.</returns>
         Task<IEnumerable<MediaSourceInfo>> GetChannelItemMediaInfo(string id, CancellationToken cancellationToken);
     }
 }

MediaBrowser.Controller/Channels/ISearchableChannel.cs

@@ -1,9 +1,10 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
-using MediaBrowser.Controller.Entities;
 
 namespace MediaBrowser.Controller.Channels
 {
@@ -17,35 +18,4 @@ namespace MediaBrowser.Controller.Channels
         /// <returns>Task{IEnumerable{ChannelItemInfo}}.</returns>
         Task<IEnumerable<ChannelItemInfo>> Search(ChannelSearchInfo searchInfo, CancellationToken cancellationToken);
     }
-
-    public interface ISupportsLatestMedia
-    {
-        /// <summary>
-        /// Gets the latest media.
-        /// </summary>
-        /// <param name="request">The request.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
-        /// <returns>Task{IEnumerable{ChannelItemInfo}}.</returns>
-        Task<IEnumerable<ChannelItemInfo>> GetLatestMedia(ChannelLatestMediaSearch request, CancellationToken cancellationToken);
-    }
-
-    public interface ISupportsDelete
-    {
-        bool CanDelete(BaseItem item);
-
-        Task DeleteItem(string id, CancellationToken cancellationToken);
-    }
-
-    public interface IDisableMediaSourceDisplay
-    {
-    }
-
-    public interface ISupportsMediaProbe
-    {
-    }
-
-    public interface IHasFolderAttributes
-    {
-        string[] Attributes { get; }
-    }
 }

MediaBrowser.Controller/Channels/ISupportsDelete.cs

@@ -0,0 +1,15 @@
+#pragma warning disable CS1591
+
+using System.Threading;
+using System.Threading.Tasks;
+using MediaBrowser.Controller.Entities;
+
+namespace MediaBrowser.Controller.Channels
+{
+    public interface ISupportsDelete
+    {
+        bool CanDelete(BaseItem item);
+
+        Task DeleteItem(string id, CancellationToken cancellationToken);
+    }
+}

MediaBrowser.Controller/Channels/ISupportsLatestMedia.cs

@@ -0,0 +1,21 @@
+#nullable disable
+
+#pragma warning disable CS1591
+
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MediaBrowser.Controller.Channels
+{
+    public interface ISupportsLatestMedia
+    {
+        /// <summary>
+        /// Gets the latest media.
+        /// </summary>
+        /// <param name="request">The request.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>The latest media.</returns>
+        Task<IEnumerable<ChannelItemInfo>> GetLatestMedia(ChannelLatestMediaSearch request, CancellationToken cancellationToken);
+    }
+}

MediaBrowser.Controller/Channels/ISupportsMediaProbe.cs

@@ -0,0 +1,9 @@
+namespace MediaBrowser.Controller.Channels
+{
+    /// <summary>
+    /// Channel supports media probe.
+    /// </summary>
+    public interface ISupportsMediaProbe
+    {
+    }
+}

MediaBrowser.Controller/Channels/InternalChannelFeatures.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA2227, CS1591
 
 using System.Collections.Generic;
 using MediaBrowser.Model.Channels;
@@ -28,7 +30,7 @@ namespace MediaBrowser.Controller.Channels
         public List<ChannelMediaContentType> ContentTypes { get; set; }
 
         /// <summary>
-        /// Represents the maximum number of records the channel allows retrieving at a time.
+        /// Gets or sets the maximum number of records the channel allows retrieving at a time.
         /// </summary>
         public int? MaxPageSize { get; set; }
 
@@ -39,7 +41,7 @@ namespace MediaBrowser.Controller.Channels
         public List<ChannelItemSortField> DefaultSortFields { get; set; }
 
         /// <summary>
-        /// Indicates if a sort ascending/descending toggle is supported or not.
+        /// Gets or sets a value indicating whether a sort ascending/descending toggle is supported or not.
         /// </summary>
         public bool SupportsSortOrderToggle { get; set; }
 

MediaBrowser.Controller/Channels/InternalChannelItemQuery.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;

MediaBrowser.Controller/Chapters/IChapterManager.cs

@@ -12,6 +12,8 @@ namespace MediaBrowser.Controller.Chapters
         /// <summary>
         /// Saves the chapters.
         /// </summary>
+        /// <param name="itemId">The item.</param>
+        /// <param name="chapters">The set of chapters.</param>
         void SaveChapters(Guid itemId, IReadOnlyList<ChapterInfo> chapters);
     }
 }

MediaBrowser.Controller/Collections/CollectionCreatedEventArgs.cs

@@ -0,0 +1,24 @@
+#nullable disable
+
+#pragma warning disable CS1591
+
+using System;
+using MediaBrowser.Controller.Entities.Movies;
+
+namespace MediaBrowser.Controller.Collections
+{
+    public class CollectionCreatedEventArgs : EventArgs
+    {
+        /// <summary>
+        /// Gets or sets the collection.
+        /// </summary>
+        /// <value>The collection.</value>
+        public BoxSet Collection { get; set; }
+
+        /// <summary>
+        /// Gets or sets the options.
+        /// </summary>
+        /// <value>The options.</value>
+        public CollectionCreationOptions Options { get; set; }
+    }
+}

MediaBrowser.Controller/Collections/CollectionCreationOptions.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -23,8 +25,8 @@ namespace MediaBrowser.Controller.Collections
 
         public Dictionary<string, string> ProviderIds { get; set; }
 
-        public string[] ItemIdList { get; set; }
+        public IReadOnlyList<string> ItemIdList { get; set; }
 
-        public Guid[] UserIds { get; set; }
+        public IReadOnlyList<Guid> UserIds { get; set; }
     }
 }

MediaBrowser.Controller/Collections/CollectionModifiedEventArgs.cs

@@ -7,23 +7,14 @@ using MediaBrowser.Controller.Entities.Movies;
 
 namespace MediaBrowser.Controller.Collections
 {
-    public class CollectionCreatedEventArgs : EventArgs
-    {
-        /// <summary>
-        /// Gets or sets the collection.
-        /// </summary>
-        /// <value>The collection.</value>
-        public BoxSet Collection { get; set; }
-
-        /// <summary>
-        /// Gets or sets the options.
-        /// </summary>
-        /// <value>The options.</value>
-        public CollectionCreationOptions Options { get; set; }
-    }
-
     public class CollectionModifiedEventArgs : EventArgs
     {
+        public CollectionModifiedEventArgs(BoxSet collection, IReadOnlyCollection<BaseItem> itemsChanged)
+        {
+            Collection = collection;
+            ItemsChanged = itemsChanged;
+        }
+
         /// <summary>
         /// Gets or sets the collection.
         /// </summary>
@@ -34,6 +25,6 @@ namespace MediaBrowser.Controller.Collections
         /// Gets or sets the items changed.
         /// </summary>
         /// <value>The items changed.</value>
-        public List<BaseItem> ItemsChanged { get; set; }
+        public IReadOnlyCollection<BaseItem> ItemsChanged { get; set; }
     }
 }

MediaBrowser.Controller/Collections/ICollectionManager.cs

@@ -14,22 +14,23 @@ namespace MediaBrowser.Controller.Collections
         /// <summary>
         /// Occurs when [collection created].
         /// </summary>
-        event EventHandler<CollectionCreatedEventArgs> CollectionCreated;
+        event EventHandler<CollectionCreatedEventArgs>? CollectionCreated;
 
         /// <summary>
         /// Occurs when [items added to collection].
         /// </summary>
-        event EventHandler<CollectionModifiedEventArgs> ItemsAddedToCollection;
+        event EventHandler<CollectionModifiedEventArgs>? ItemsAddedToCollection;
 
         /// <summary>
         /// Occurs when [items removed from collection].
         /// </summary>
-        event EventHandler<CollectionModifiedEventArgs> ItemsRemovedFromCollection;
+        event EventHandler<CollectionModifiedEventArgs>? ItemsRemovedFromCollection;
 
         /// <summary>
         /// Creates the collection.
         /// </summary>
         /// <param name="options">The options.</param>
+        /// <returns>BoxSet wrapped in an awaitable task.</returns>
         Task<BoxSet> CreateCollectionAsync(CollectionCreationOptions options);
 
         /// <summary>

MediaBrowser.Controller/Devices/IDeviceManager.cs

@@ -1,8 +1,13 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
+using System.Threading.Tasks;
 using Jellyfin.Data.Entities;
+using Jellyfin.Data.Entities.Security;
 using Jellyfin.Data.Events;
+using Jellyfin.Data.Queries;
 using MediaBrowser.Model.Devices;
 using MediaBrowser.Model.Querying;
 using MediaBrowser.Model.Session;
@@ -13,42 +18,63 @@ namespace MediaBrowser.Controller.Devices
     {
         event EventHandler<GenericEventArgs<Tuple<string, DeviceOptions>>> DeviceOptionsUpdated;
 
+        /// <summary>
+        /// Creates a new device.
+        /// </summary>
+        /// <param name="device">The device to create.</param>
+        /// <returns>A <see cref="Task{Device}"/> representing the creation of the device.</returns>
+        Task<Device> CreateDevice(Device device);
+
         /// <summary>
         /// Saves the capabilities.
         /// </summary>
-        /// <param name="reportedId">The reported identifier.</param>
+        /// <param name="deviceId">The device id.</param>
         /// <param name="capabilities">The capabilities.</param>
-        /// <returns>Task.</returns>
-        void SaveCapabilities(string reportedId, ClientCapabilities capabilities);
+        void SaveCapabilities(string deviceId, ClientCapabilities capabilities);
 
         /// <summary>
         /// Gets the capabilities.
         /// </summary>
-        /// <param name="reportedId">The reported identifier.</param>
+        /// <param name="deviceId">The device id.</param>
         /// <returns>ClientCapabilities.</returns>
-        ClientCapabilities GetCapabilities(string reportedId);
+        ClientCapabilities GetCapabilities(string deviceId);
 
         /// <summary>
         /// Gets the device information.
         /// </summary>
         /// <param name="id">The identifier.</param>
         /// <returns>DeviceInfo.</returns>
-        DeviceInfo GetDevice(string id);
+        Task<DeviceInfo> GetDevice(string id);
+
+        /// <summary>
+        /// Gets devices based on the provided query.
+        /// </summary>
+        /// <param name="query">The device query.</param>
+        /// <returns>A <see cref="Task{QueryResult}"/> representing the retrieval of the devices.</returns>
+        Task<QueryResult<Device>> GetDevices(DeviceQuery query);
+
+        Task<QueryResult<DeviceInfo>> GetDeviceInfos(DeviceQuery query);
 
         /// <summary>
         /// Gets the devices.
         /// </summary>
-        /// <param name="query">The query.</param>
+        /// <param name="userId">The user's id, or <c>null</c>.</param>
+        /// <param name="supportsSync">A value indicating whether the device supports sync, or <c>null</c>.</param>
         /// <returns>IEnumerable&lt;DeviceInfo&gt;.</returns>
-        QueryResult<DeviceInfo> GetDevices(DeviceQuery query);
+        Task<QueryResult<DeviceInfo>> GetDevicesForUser(Guid? userId, bool? supportsSync);
+
+        Task DeleteDevice(Device device);
 
         /// <summary>
         /// Determines whether this instance [can access device] the specified user identifier.
         /// </summary>
+        /// <param name="user">The user to test.</param>
+        /// <param name="deviceId">The device id to test.</param>
+        /// <returns>Whether the user can access the device.</returns>
         bool CanAccessDevice(User user, string deviceId);
 
-        void UpdateDeviceOptions(string deviceId, DeviceOptions options);
+        Task UpdateDeviceOptions(string deviceId, string deviceName);
 
-        DeviceOptions GetDeviceOptions(string deviceId);
+        Task<DeviceOptions> GetDeviceOptions(string deviceId);
     }
 }

MediaBrowser.Controller/Dlna/IDlnaManager.cs

@@ -20,7 +20,7 @@ namespace MediaBrowser.Controller.Dlna
         /// </summary>
         /// <param name="headers">The headers.</param>
         /// <returns>DeviceProfile.</returns>
-        DeviceProfile GetProfile(IHeaderDictionary headers);
+        DeviceProfile? GetProfile(IHeaderDictionary headers);
 
         /// <summary>
         /// Gets the default profile.
@@ -51,14 +51,14 @@ namespace MediaBrowser.Controller.Dlna
         /// </summary>
         /// <param name="id">The identifier.</param>
         /// <returns>DeviceProfile.</returns>
-        DeviceProfile GetProfile(string id);
+        DeviceProfile? GetProfile(string id);
 
         /// <summary>
         /// Gets the profile.
         /// </summary>
         /// <param name="deviceInfo">The device information.</param>
         /// <returns>DeviceProfile.</returns>
-        DeviceProfile GetProfile(DeviceIdentification deviceInfo);
+        DeviceProfile? GetProfile(DeviceIdentification deviceInfo);
 
         /// <summary>
         /// Gets the server description XML.
@@ -74,6 +74,6 @@ namespace MediaBrowser.Controller.Dlna
         /// </summary>
         /// <param name="filename">The filename.</param>
         /// <returns>DlnaIconResponse.</returns>
-        ImageStream GetIcon(string filename);
+        ImageStream? GetIcon(string filename);
     }
 }

MediaBrowser.Controller/Drawing/IImageEncoder.cs

@@ -1,5 +1,4 @@
 #pragma warning disable CS1591
-#nullable enable
 
 using System;
 using System.Collections.Generic;
@@ -58,6 +57,15 @@ namespace MediaBrowser.Controller.Drawing
         /// <summary>
         /// Encode an image.
         /// </summary>
+        /// <param name="inputPath">Input path of image.</param>
+        /// <param name="dateModified">Date modified.</param>
+        /// <param name="outputPath">Output path of image.</param>
+        /// <param name="autoOrient">Auto-orient image.</param>
+        /// <param name="orientation">Desired orientation of image.</param>
+        /// <param name="quality">Quality of encoded image.</param>
+        /// <param name="options">Image processing options.</param>
+        /// <param name="outputFormat">Image format of output.</param>
+        /// <returns>Path of encoded image.</returns>
         string EncodeImage(string inputPath, DateTime dateModified, string outputPath, bool autoOrient, ImageOrientation? orientation, int quality, ImageProcessingOptions options, ImageFormat outputFormat);
 
         /// <summary>

MediaBrowser.Controller/Drawing/IImageProcessor.cs

@@ -1,5 +1,4 @@
 #pragma warning disable CS1591
-#nullable enable
 
 using System;
 using System.Collections.Generic;
@@ -59,7 +58,7 @@ namespace MediaBrowser.Controller.Drawing
         /// <returns>Guid.</returns>
         string GetImageCacheTag(BaseItem item, ItemImageInfo image);
 
-        string GetImageCacheTag(BaseItem item, ChapterInfo info);
+        string GetImageCacheTag(BaseItem item, ChapterInfo chapter);
 
         string? GetImageCacheTag(User user);
 

MediaBrowser.Controller/Drawing/ImageCollageOptions.cs

@@ -1,3 +1,7 @@
+#nullable disable
+
+using System.Collections.Generic;
+
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Controller.Drawing
@@ -8,7 +12,7 @@ namespace MediaBrowser.Controller.Drawing
         /// Gets or sets the input paths.
         /// </summary>
         /// <value>The input paths.</value>
-        public string[] InputPaths { get; set; }
+        public IReadOnlyList<string> InputPaths { get; set; }
 
         /// <summary>
         /// Gets or sets the output path.

MediaBrowser.Controller/Drawing/ImageHelper.cs

@@ -1,5 +1,4 @@
 #pragma warning disable CS1591
-#nullable enable
 
 using MediaBrowser.Model.Drawing;
 

MediaBrowser.Controller/Drawing/ImageProcessingOptions.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;

MediaBrowser.Controller/Drawing/ImageProcessorExtensions.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using MediaBrowser.Controller.Entities;

MediaBrowser.Controller/Drawing/ImageStream.cs

@@ -1,4 +1,4 @@
-#pragma warning disable CS1591
+#pragma warning disable CA1711, CS1591
 
 using System;
 using System.IO;
@@ -8,11 +8,16 @@ namespace MediaBrowser.Controller.Drawing
 {
     public class ImageStream : IDisposable
     {
+        public ImageStream(Stream stream)
+        {
+            Stream = stream;
+        }
+
         /// <summary>
-        /// Gets or sets the stream.
+        /// Gets the stream.
         /// </summary>
         /// <value>The stream.</value>
-        public Stream Stream { get; set; }
+        public Stream Stream { get; }
 
         /// <summary>
         /// Gets or sets the format.
@@ -22,9 +27,15 @@ namespace MediaBrowser.Controller.Drawing
 
         public void Dispose()
         {
-            if (Stream != null)
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (disposing)
             {
-                Stream.Dispose();
+                Stream?.Dispose();
             }
         }
     }

MediaBrowser.Controller/Dto/DtoOptions.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -16,6 +18,28 @@ namespace MediaBrowser.Controller.Dto
             ItemFields.RefreshState
         };
 
+        private static readonly ImageType[] AllImageTypes = Enum.GetValues<ImageType>();
+
+        private static readonly ItemFields[] AllItemFields = Enum.GetValues<ItemFields>()
+            .Except(DefaultExcludedFields)
+            .ToArray();
+
+        public DtoOptions()
+            : this(true)
+        {
+        }
+
+        public DtoOptions(bool allFields)
+        {
+            ImageTypeLimit = int.MaxValue;
+            EnableImages = true;
+            EnableUserData = true;
+            AddCurrentProgram = true;
+
+            Fields = allFields ? AllItemFields : Array.Empty<ItemFields>();
+            ImageTypes = AllImageTypes;
+        }
+
         public IReadOnlyList<ItemFields> Fields { get; set; }
 
         public IReadOnlyList<ImageType> ImageTypes { get; set; }
@@ -30,34 +54,9 @@ namespace MediaBrowser.Controller.Dto
 
         public bool AddCurrentProgram { get; set; }
 
-        public DtoOptions()
-            : this(true)
-        {
-        }
-
-        private static readonly ImageType[] AllImageTypes = Enum.GetNames(typeof(ImageType))
-            .Select(i => (ImageType)Enum.Parse(typeof(ImageType), i, true))
-            .ToArray();
-
-        private static readonly ItemFields[] AllItemFields = Enum.GetNames(typeof(ItemFields))
-            .Select(i => (ItemFields)Enum.Parse(typeof(ItemFields), i, true))
-            .Except(DefaultExcludedFields)
-            .ToArray();
-
         public bool ContainsField(ItemFields field)
             => Fields.Contains(field);
 
-        public DtoOptions(bool allFields)
-        {
-            ImageTypeLimit = int.MaxValue;
-            EnableImages = true;
-            EnableUserData = true;
-            AddCurrentProgram = true;
-
-            Fields = allFields ? AllItemFields : Array.Empty<ItemFields>();
-            ImageTypes = AllImageTypes;
-        }
-
         public int GetImageLimit(ImageType type)
         {
             if (EnableImages && ImageTypes.Contains(type))

MediaBrowser.Controller/Dto/IDtoService.cs

@@ -1,3 +1,6 @@
+#nullable disable
+#pragma warning disable CA1002
+
 using System.Collections.Generic;
 using Jellyfin.Data.Entities;
 using MediaBrowser.Controller.Entities;
@@ -34,11 +37,17 @@ namespace MediaBrowser.Controller.Dto
         /// <param name="options">The options.</param>
         /// <param name="user">The user.</param>
         /// <param name="owner">The owner.</param>
+        /// <returns>The <see cref="IReadOnlyList{T}"/> of <see cref="BaseItemDto"/>.</returns>
         IReadOnlyList<BaseItemDto> GetBaseItemDtos(IReadOnlyList<BaseItem> items, DtoOptions options, User user = null, BaseItem owner = null);
 
         /// <summary>
         /// Gets the item by name dto.
         /// </summary>
+        /// <param name="item">The item.</param>
+        /// <param name="options">The dto options.</param>
+        /// <param name="taggedItems">The list of tagged items.</param>
+        /// <param name="user">The user.</param>
+        /// <returns>The item dto.</returns>
         BaseItemDto GetItemByNameDto(BaseItem item, DtoOptions options, List<BaseItem> taggedItems, User user = null);
     }
 }

MediaBrowser.Controller/Entities/AggregateFolder.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 using System.Collections.Concurrent;
@@ -16,30 +18,23 @@ namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
     /// Specialized folder that can have items added to it's children by external entities.
-    /// Used for our RootFolder so plug-ins can add items.
+    /// Used for our RootFolder so plugins can add items.
     /// </summary>
     public class AggregateFolder : Folder
     {
-        public AggregateFolder()
-        {
-            PhysicalLocationsList = Array.Empty<string>();
-        }
-
-        [JsonIgnore]
-        public override bool IsPhysicalRoot => true;
-
-        public override bool CanDelete()
-        {
-            return false;
-        }
-
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
+        private readonly object _childIdsLock = new object();
 
         /// <summary>
         /// The _virtual children.
         /// </summary>
         private readonly ConcurrentBag<BaseItem> _virtualChildren = new ConcurrentBag<BaseItem>();
+        private bool _requiresRefresh;
+        private Guid[] _childrenIds = null;
+
+        public AggregateFolder()
+        {
+            PhysicalLocationsList = Array.Empty<string>();
+        }
 
         /// <summary>
         /// Gets the virtual children.
@@ -47,19 +42,27 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The virtual children.</value>
         public ConcurrentBag<BaseItem> VirtualChildren => _virtualChildren;
 
+        [JsonIgnore]
+        public override bool IsPhysicalRoot => true;
+
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
         [JsonIgnore]
         public override string[] PhysicalLocations => PhysicalLocationsList;
 
         public string[] PhysicalLocationsList { get; set; }
 
+        public override bool CanDelete()
+        {
+            return false;
+        }
+
         protected override FileSystemMetadata[] GetFileSystemChildren(IDirectoryService directoryService)
         {
             return CreateResolveArgs(directoryService, true).FileSystemChildren;
         }
 
-        private Guid[] _childrenIds = null;
-        private readonly object _childIdsLock = new object();
-
         protected override List<BaseItem> LoadChildren()
         {
             lock (_childIdsLock)
@@ -83,7 +86,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private bool _requiresRefresh;
         public override bool RequiresRefresh()
         {
             var changed = base.RequiresRefresh() || _requiresRefresh;
@@ -103,11 +105,11 @@ namespace MediaBrowser.Controller.Entities
             return changed;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
             ClearCache();
 
-            var changed = base.BeforeMetadataRefresh(replaceAllMetdata) || _requiresRefresh;
+            var changed = base.BeforeMetadataRefresh(replaceAllMetadata) || _requiresRefresh;
             _requiresRefresh = false;
             return changed;
         }
@@ -120,8 +122,7 @@ namespace MediaBrowser.Controller.Entities
 
             var args = new ItemResolveArgs(ConfigurationManager.ApplicationPaths, directoryService)
             {
-                FileInfo = FileSystem.GetDirectoryInfo(path),
-                Path = path
+                FileInfo = FileSystem.GetDirectoryInfo(path)
             };
 
             // Gather child folder and files
@@ -153,11 +154,11 @@ namespace MediaBrowser.Controller.Entities
             return base.GetNonCachedChildren(directoryService).Concat(_virtualChildren);
         }
 
-        protected override async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             ClearCache();
 
-            await base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService)
+            await base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken)
                 .ConfigureAwait(false);
 
             ClearCache();
@@ -167,7 +168,7 @@ namespace MediaBrowser.Controller.Entities
         /// Adds the virtual child.
         /// </summary>
         /// <param name="child">The child.</param>
-        /// <exception cref="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throws if child is null.</exception>
         public void AddVirtualChild(BaseItem child)
         {
             if (child == null)
@@ -183,7 +184,7 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="id">The id.</param>
         /// <returns>BaseItem.</returns>
-        /// <exception cref="ArgumentNullException">id</exception>
+        /// <exception cref="ArgumentNullException">The id is empty.</exception>
         public BaseItem FindVirtualChild(Guid id)
         {
             if (id.Equals(Guid.Empty))

MediaBrowser.Controller/Entities/Audio/Audio.cs

@@ -1,7 +1,10 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA1724, CA1826, CS1591
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Text.Json.Serialization;
 using Jellyfin.Data.Enums;
@@ -22,6 +25,12 @@ namespace MediaBrowser.Controller.Entities.Audio
         IHasLookupInfo<SongInfo>,
         IHasMediaSources
     {
+        public Audio()
+        {
+            Artists = Array.Empty<string>();
+            AlbumArtists = Array.Empty<string>();
+        }
+
         /// <inheritdoc />
         [JsonIgnore]
         public IReadOnlyList<string> Artists { get; set; }
@@ -30,22 +39,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public IReadOnlyList<string> AlbumArtists { get; set; }
 
-        public Audio()
-        {
-            Artists = Array.Empty<string>();
-            AlbumArtists = Array.Empty<string>();
-        }
-
-        public override double GetDefaultPrimaryImageAspectRatio()
-        {
-            return 1;
-        }
-
         [JsonIgnore]
         public override bool SupportsPlayedStatus => true;
 
         [JsonIgnore]
-        public override bool SupportsPeople => false;
+        public override bool SupportsPeople => true;
 
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
@@ -59,11 +57,6 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override Folder LatestItemsIndexContainer => AlbumEntity;
 
-        public override bool CanDownload()
-        {
-            return IsFileProtocol;
-        }
-
         [JsonIgnore]
         public MusicAlbum AlbumEntity => FindParent<MusicAlbum>();
 
@@ -74,25 +67,35 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override string MediaType => Model.Entities.MediaType.Audio;
 
+        public override double GetDefaultPrimaryImageAspectRatio()
+        {
+            return 1;
+        }
+
+        public override bool CanDownload()
+        {
+            return IsFileProtocol;
+        }
+
         /// <summary>
         /// Creates the name of the sort.
         /// </summary>
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("0000 - ") : "")
-                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ") : "") + Name;
+            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty)
+                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty) + Name;
         }
 
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
 
-            var songKey = IndexNumber.HasValue ? IndexNumber.Value.ToString("0000") : string.Empty;
+            var songKey = IndexNumber.HasValue ? IndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) : string.Empty;
 
             if (ParentIndexNumber.HasValue)
             {
-                songKey = ParentIndexNumber.Value.ToString("0000") + "-" + songKey;
+                songKey = ParentIndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) + "-" + songKey;
             }
 
             songKey += Name;

MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Collections.Generic;

MediaBrowser.Controller/Entities/Audio/IHasMusicGenres.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 namespace MediaBrowser.Controller.Entities.Audio
 {

MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1721, CA1826, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -21,18 +23,18 @@ namespace MediaBrowser.Controller.Entities.Audio
     /// </summary>
     public class MusicAlbum : Folder, IHasAlbumArtist, IHasArtist, IHasMusicGenres, IHasLookupInfo<AlbumInfo>, IMetadataContainer
     {
-        /// <inheritdoc />
-        public IReadOnlyList<string> AlbumArtists { get; set; }
-
-        /// <inheritdoc />
-        public IReadOnlyList<string> Artists { get; set; }
-
         public MusicAlbum()
         {
             Artists = Array.Empty<string>();
             AlbumArtists = Array.Empty<string>();
         }
 
+        /// <inheritdoc />
+        public IReadOnlyList<string> AlbumArtists { get; set; }
+
+        /// <inheritdoc />
+        public IReadOnlyList<string> Artists { get; set; }
+
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
 
@@ -42,6 +44,25 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public MusicArtist MusicArtist => GetMusicArtist(new DtoOptions(true));
 
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        [JsonIgnore]
+        public override bool SupportsCumulativeRunTimeTicks => true;
+
+        [JsonIgnore]
+        public string AlbumArtist => AlbumArtists.FirstOrDefault();
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        /// <summary>
+        /// Gets the tracks.
+        /// </summary>
+        /// <value>The tracks.</value>
+        [JsonIgnore]
+        public IEnumerable<Audio> Tracks => GetRecursiveChildren(i => i is Audio).Cast<Audio>();
+
         public MusicArtist GetMusicArtist(DtoOptions options)
         {
             var parents = GetParents();
@@ -62,25 +83,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return null;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
-
-        [JsonIgnore]
-        public override bool SupportsCumulativeRunTimeTicks => true;
-
-        [JsonIgnore]
-        public string AlbumArtist => AlbumArtists.FirstOrDefault();
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        /// <summary>
-        /// Gets the tracks.
-        /// </summary>
-        /// <value>The tracks.</value>
-        [JsonIgnore]
-        public IEnumerable<Audio> Tracks => GetRecursiveChildren(i => i is Audio).Cast<Audio>();
-
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             return Tracks;

MediaBrowser.Controller/Entities/Audio/MusicArtist.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -6,9 +8,9 @@ using System.Linq;
 using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
+using Diacritics.Extensions;
 using Jellyfin.Data.Entities;
 using Jellyfin.Data.Enums;
-using MediaBrowser.Controller.Extensions;
 using MediaBrowser.Controller.Providers;
 using MediaBrowser.Model.Entities;
 using Microsoft.Extensions.Logging;
@@ -42,6 +44,36 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override bool SupportsPlayedStatus => false;
 
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override IEnumerable<BaseItem> Children
+        {
+            get
+            {
+                if (IsAccessedByName)
+                {
+                    return new List<BaseItem>();
+                }
+
+                return base.Children;
+            }
+        }
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        public static string GetPath(string name)
+        {
+            return GetPath(name, true);
+        }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             return 1;
@@ -63,20 +95,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override IEnumerable<BaseItem> Children
-        {
-            get
-            {
-                if (IsAccessedByName)
-                {
-                    return new List<BaseItem>();
-                }
-
-                return base.Children;
-            }
-        }
-
         public override int GetChildCount(User user)
         {
             return IsAccessedByName ? 0 : base.GetChildCount(user);
@@ -92,7 +110,7 @@ namespace MediaBrowser.Controller.Entities.Audio
             return base.IsSaveLocalMetadataEnabled();
         }
 
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             if (IsAccessedByName)
             {
@@ -100,7 +118,7 @@ namespace MediaBrowser.Controller.Entities.Audio
                 return Task.CompletedTask;
             }
 
-            return base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService);
+            return base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken);
         }
 
         public override List<string> GetUserDataKeys()
@@ -111,14 +129,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return list;
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
         /// <summary>
         /// Gets the user data key.
         /// </summary>
@@ -165,14 +175,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return info;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        public static string GetPath(string name)
-        {
-            return GetPath(name, true);
-        }
-
         public static string GetPath(string name, bool normalizeName)
         {
             // Trim the period at the end because windows will have a hard time with that
@@ -206,9 +208,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Option to replace metadata.</param>
+        /// <returns>True if metadata changed.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (IsAccessedByName)
             {

MediaBrowser.Controller/Entities/Audio/MusicGenre.cs

@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities.Audio
@@ -13,6 +15,26 @@ namespace MediaBrowser.Controller.Entities.Audio
     /// </summary>
     public class MusicGenre : BaseItem, IItemByName
     {
+        [JsonIgnore]
+        public override bool SupportsAddingToPlaylist => true;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
+        [JsonIgnore]
+        public override bool IsDisplayedAsFolder => true;
+
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -26,23 +48,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return GetUserDataKeys()[0];
         }
 
-        [JsonIgnore]
-        public override bool SupportsAddingToPlaylist => true;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
-        [JsonIgnore]
-        public override bool IsDisplayedAsFolder => true;
-
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             return 1;
@@ -58,9 +63,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return true;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public IList<BaseItem> GetTaggedItems(InternalItemsQuery query)
         {
             query.GenreIds = new[] { Id };
@@ -104,9 +106,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Option to replace metadata.</param>
+        /// <returns>True if metadata changed.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))

MediaBrowser.Controller/Entities/AudioBook.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1724, CS1591
 
 using System;
 using System.Text.Json.Serialization;

MediaBrowser.Controller/Entities/BaseItemExtensions.cs

@@ -1,4 +1,3 @@
-#nullable enable
 #pragma warning disable CS1591
 
 using System;
@@ -45,7 +44,7 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="file">The file.</param>
         public static void SetImagePath(this BaseItem item, ImageType imageType, string file)
         {
-            if (file.StartsWith("http", System.StringComparison.OrdinalIgnoreCase))
+            if (file.StartsWith("http", StringComparison.OrdinalIgnoreCase))
             {
                 item.SetImage(
                 new ItemImageInfo
@@ -65,6 +64,8 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="source">The source object.</param>
         /// <param name="dest">The destination object.</param>
+        /// <typeparam name="T">Source type.</typeparam>
+        /// <typeparam name="TU">Destination type.</typeparam>
         public static void DeepCopy<T, TU>(this T source, TU dest)
             where T : BaseItem
             where TU : BaseItem
@@ -110,6 +111,9 @@ namespace MediaBrowser.Controller.Entities
         /// Copies all properties on newly created object. Skips properties that do not exist.
         /// </summary>
         /// <param name="source">The source object.</param>
+        /// <typeparam name="T">Source type.</typeparam>
+        /// <typeparam name="TU">Destination type.</typeparam>
+        /// <returns>Destination object.</returns>
         public static TU DeepCopy<T, TU>(this T source)
             where T : BaseItem
             where TU : BaseItem, new()

MediaBrowser.Controller/Entities/BasePluginFolder.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Text.Json.Serialization;
@@ -13,6 +15,12 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual string CollectionType => null;
 
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override bool CanDelete()
         {
             return false;
@@ -22,11 +30,5 @@ namespace MediaBrowser.Controller.Entities
         {
             return true;
         }
-
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }

MediaBrowser.Controller/Entities/Book.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -10,6 +12,11 @@ namespace MediaBrowser.Controller.Entities
 {
     public class Book : BaseItem, IHasLookupInfo<BookInfo>, IHasSeries
     {
+        public Book()
+        {
+            this.RunTimeTicks = TimeSpan.TicksPerSecond;
+        }
+
         [JsonIgnore]
         public override string MediaType => Model.Entities.MediaType.Book;
 
@@ -26,11 +33,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public Guid SeriesId { get; set; }
 
-        public Book()
-        {
-            this.RunTimeTicks = TimeSpan.TicksPerSecond;
-        }
-
         public string FindSeriesSortName()
         {
             return SeriesName;

MediaBrowser.Controller/Entities/CollectionFolder.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -8,7 +10,7 @@ using System.Text.Json;
 using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
-using MediaBrowser.Common.Json;
+using Jellyfin.Extensions.Json;
 using MediaBrowser.Controller.IO;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Providers;
@@ -27,30 +29,65 @@ namespace MediaBrowser.Controller.Entities
     public class CollectionFolder : Folder, ICollectionFolder
     {
         private static readonly JsonSerializerOptions _jsonOptions = JsonDefaults.Options;
-        public static IXmlSerializer XmlSerializer { get; set; }
-
-        public static IServerApplicationHost ApplicationHost { get; set; }
+        private static readonly Dictionary<string, LibraryOptions> _libraryOptions = new Dictionary<string, LibraryOptions>();
+        private bool _requiresRefresh;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CollectionFolder"/> class.
+        /// </summary>
         public CollectionFolder()
         {
             PhysicalLocationsList = Array.Empty<string>();
             PhysicalFolderIds = Array.Empty<Guid>();
         }
 
+        /// <summary>
+        /// Gets the display preferences id.
+        /// </summary>
+        /// <remarks>
+        /// Allow different display preferences for each collection folder.
+        /// </remarks>
+        /// <value>The display prefs id.</value>
+        [JsonIgnore]
+        public override Guid DisplayPreferencesId => Id;
+
+        [JsonIgnore]
+        public override string[] PhysicalLocations => PhysicalLocationsList;
+
+        public string[] PhysicalLocationsList { get; set; }
+
+        public Guid[] PhysicalFolderIds { get; set; }
+
+        public static IXmlSerializer XmlSerializer { get; set; }
+
+        public static IServerApplicationHost ApplicationHost { get; set; }
+
         [JsonIgnore]
         public override bool SupportsPlayedStatus => false;
 
         [JsonIgnore]
         public override bool SupportsInheritedParentImages => false;
 
+        public string CollectionType { get; set; }
+
+        /// <summary>
+        /// Gets the item's children.
+        /// </summary>
+        /// <remarks>
+        /// Our children are actually just references to the ones in the physical root...
+        /// </remarks>
+        /// <value>The actual children.</value>
+        [JsonIgnore]
+        public override IEnumerable<BaseItem> Children => GetActualChildren();
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override bool CanDelete()
         {
             return false;
         }
 
-        public string CollectionType { get; set; }
-
-        private static readonly Dictionary<string, LibraryOptions> LibraryOptions = new Dictionary<string, LibraryOptions>();
         public LibraryOptions GetLibraryOptions()
         {
             return GetLibraryOptions(Path);
@@ -60,9 +97,7 @@ namespace MediaBrowser.Controller.Entities
         {
             try
             {
-                var result = XmlSerializer.DeserializeFromFile(typeof(LibraryOptions), GetLibraryOptionsPath(path)) as LibraryOptions;
-
-                if (result == null)
+                if (XmlSerializer.DeserializeFromFile(typeof(LibraryOptions), GetLibraryOptionsPath(path)) is not LibraryOptions result)
                 {
                     return new LibraryOptions();
                 }
@@ -105,12 +140,12 @@ namespace MediaBrowser.Controller.Entities
 
         public static LibraryOptions GetLibraryOptions(string path)
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                if (!LibraryOptions.TryGetValue(path, out var options))
+                if (!_libraryOptions.TryGetValue(path, out var options))
                 {
                     options = LoadLibraryOptions(path);
-                    LibraryOptions[path] = options;
+                    _libraryOptions[path] = options;
                 }
 
                 return options;
@@ -119,9 +154,9 @@ namespace MediaBrowser.Controller.Entities
 
         public static void SaveLibraryOptions(string path, LibraryOptions options)
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                LibraryOptions[path] = options;
+                _libraryOptions[path] = options;
 
                 var clone = JsonSerializer.Deserialize<LibraryOptions>(JsonSerializer.SerializeToUtf8Bytes(options, _jsonOptions), _jsonOptions);
                 foreach (var mediaPath in clone.PathInfos)
@@ -138,37 +173,22 @@ namespace MediaBrowser.Controller.Entities
 
         public static void OnCollectionFolderChange()
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                LibraryOptions.Clear();
+                _libraryOptions.Clear();
             }
         }
 
-        /// <summary>
-        /// Allow different display preferences for each collection folder.
-        /// </summary>
-        /// <value>The display prefs id.</value>
-        [JsonIgnore]
-        public override Guid DisplayPreferencesId => Id;
-
-        [JsonIgnore]
-        public override string[] PhysicalLocations => PhysicalLocationsList;
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
         }
 
-        public string[] PhysicalLocationsList { get; set; }
-
-        public Guid[] PhysicalFolderIds { get; set; }
-
         protected override FileSystemMetadata[] GetFileSystemChildren(IDirectoryService directoryService)
         {
             return CreateResolveArgs(directoryService, true).FileSystemChildren;
         }
 
-        private bool _requiresRefresh;
         public override bool RequiresRefresh()
         {
             var changed = base.RequiresRefresh() || _requiresRefresh;
@@ -200,9 +220,9 @@ namespace MediaBrowser.Controller.Entities
             return changed;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var changed = base.BeforeMetadataRefresh(replaceAllMetdata) || _requiresRefresh;
+            var changed = base.BeforeMetadataRefresh(replaceAllMetadata) || _requiresRefresh;
             _requiresRefresh = false;
             return changed;
         }
@@ -271,7 +291,6 @@ namespace MediaBrowser.Controller.Entities
             var args = new ItemResolveArgs(ConfigurationManager.ApplicationPaths, directoryService)
             {
                 FileInfo = FileSystem.GetDirectoryInfo(path),
-                Path = path,
                 Parent = GetParent() as Folder,
                 CollectionType = CollectionType
             };
@@ -298,27 +317,20 @@ namespace MediaBrowser.Controller.Entities
 
         /// <summary>
         /// Compare our current children (presumably just read from the repo) with the current state of the file system and adjust for any changes
-        /// ***Currently does not contain logic to maintain items that are unavailable in the file system***
+        /// ***Currently does not contain logic to maintain items that are unavailable in the file system***.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
         /// <param name="refreshChildMetadata">if set to <c>true</c> [refresh child metadata].</param>
         /// <param name="refreshOptions">The refresh options.</param>
         /// <param name="directoryService">The directory service.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             return Task.CompletedTask;
         }
 
-        /// <summary>
-        /// Our children are actually just references to the ones in the physical root...
-        /// </summary>
-        /// <value>The actual children.</value>
-        [JsonIgnore]
-        public override IEnumerable<BaseItem> Children => GetActualChildren();
-
         public IEnumerable<BaseItem> GetActualChildren()
         {
             return GetPhysicalFolders(true).SelectMany(c => c.Children);
@@ -355,9 +367,7 @@ namespace MediaBrowser.Controller.Entities
 
             if (result.Count == 0)
             {
-                var folder = LibraryManager.FindByPath(path, true) as Folder;
-
-                if (folder != null)
+                if (LibraryManager.FindByPath(path, true) is Folder folder)
                 {
                     result.Add(folder);
                 }
@@ -365,8 +375,5 @@ namespace MediaBrowser.Controller.Entities
 
             return result;
         }
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }

MediaBrowser.Controller/Entities/Extensions.cs

@@ -1,6 +1,8 @@
+#nullable disable
+
 using System;
 using System.Linq;
-using MediaBrowser.Common.Extensions;
+using Jellyfin.Extensions;
 using MediaBrowser.Model.Entities;
 
 namespace MediaBrowser.Controller.Entities
@@ -13,6 +15,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Adds the trailer URL.
         /// </summary>
+        /// <param name="item">Media item.</param>
+        /// <param name="url">Trailer URL.</param>
         public static void AddTrailerUrl(this BaseItem item, string url)
         {
             if (string.IsNullOrEmpty(url))

MediaBrowser.Controller/Entities/Folder.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA1721, CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -35,6 +37,11 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Folder : BaseItem
     {
+        public Folder()
+        {
+            LinkedChildren = Array.Empty<LinkedChild>();
+        }
+
         public static IUserViewManager UserViewManager { get; set; }
 
         /// <summary>
@@ -48,11 +55,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public DateTime? DateLastMediaAdded { get; set; }
 
-        public Folder()
-        {
-            LinkedChildren = Array.Empty<LinkedChild>();
-        }
-
         [JsonIgnore]
         public override bool SupportsThemeMedia => true;
 
@@ -84,6 +86,87 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual bool SupportsDateLastMediaAdded => false;
 
+        [JsonIgnore]
+        public override string FileNameWithoutExtension
+        {
+            get
+            {
+                if (IsFileProtocol)
+                {
+                    return System.IO.Path.GetFileName(Path);
+                }
+
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Gets the actual children.
+        /// </summary>
+        /// <value>The actual children.</value>
+        [JsonIgnore]
+        public virtual IEnumerable<BaseItem> Children => LoadChildren();
+
+        /// <summary>
+        /// Gets thread-safe access to all recursive children of this folder - without regard to user.
+        /// </summary>
+        /// <value>The recursive children.</value>
+        [JsonIgnore]
+        public IEnumerable<BaseItem> RecursiveChildren => GetRecursiveChildren();
+
+        [JsonIgnore]
+        protected virtual bool SupportsShortcutChildren => false;
+
+        protected virtual bool FilterLinkedChildrenPerUser => false;
+
+        [JsonIgnore]
+        protected override bool SupportsOwnedItems => base.SupportsOwnedItems || SupportsShortcutChildren;
+
+        [JsonIgnore]
+        public virtual bool SupportsUserDataFromChildren
+        {
+            get
+            {
+                // These are just far too slow.
+                if (this is ICollectionFolder)
+                {
+                    return false;
+                }
+
+                if (this is UserView)
+                {
+                    return false;
+                }
+
+                if (this is UserRootFolder)
+                {
+                    return false;
+                }
+
+                if (this is Channel)
+                {
+                    return false;
+                }
+
+                if (SourceType != SourceType.Library)
+                {
+                    return false;
+                }
+
+                if (this is IItemByName)
+                {
+                    if (this is not IHasDualAccess hasDualAccess || hasDualAccess.IsAccessedByName)
+                    {
+                        return false;
+                    }
+                }
+
+                return true;
+            }
+        }
+
+        public static ICollectionManager CollectionManager { get; set; }
+
         public override bool CanDelete()
         {
             if (IsRoot)
@@ -106,20 +189,6 @@ namespace MediaBrowser.Controller.Entities
             return baseResult;
         }
 
-        [JsonIgnore]
-        public override string FileNameWithoutExtension
-        {
-            get
-            {
-                if (IsFileProtocol)
-                {
-                    return System.IO.Path.GetFileName(Path);
-                }
-
-                return null;
-            }
-        }
-
         protected override bool IsAllowTagFilterEnforced()
         {
             if (this is ICollectionFolder)
@@ -135,17 +204,12 @@ namespace MediaBrowser.Controller.Entities
             return true;
         }
 
-        [JsonIgnore]
-        protected virtual bool SupportsShortcutChildren => false;
-
         /// <summary>
         /// Adds the child.
         /// </summary>
         /// <param name="item">The item.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
-        /// <returns>Task.</returns>
-        /// <exception cref="InvalidOperationException">Unable to add  + item.Name</exception>
-        public void AddChild(BaseItem item, CancellationToken cancellationToken)
+        /// <exception cref="InvalidOperationException">Unable to add  + item.Name.</exception>
+        public void AddChild(BaseItem item)
         {
             item.SetParent(this);
 
@@ -167,23 +231,9 @@ namespace MediaBrowser.Controller.Entities
             LibraryManager.CreateItem(item, this);
         }
 
-        /// <summary>
-        /// Gets the actual children.
-        /// </summary>
-        /// <value>The actual children.</value>
-        [JsonIgnore]
-        public virtual IEnumerable<BaseItem> Children => LoadChildren();
-
-        /// <summary>
-        /// thread-safe access to all recursive children of this folder - without regard to user.
-        /// </summary>
-        /// <value>The recursive children.</value>
-        [JsonIgnore]
-        public IEnumerable<BaseItem> RecursiveChildren => GetRecursiveChildren();
-
         public override bool IsVisible(User user)
         {
-            if (this is ICollectionFolder && !(this is BasePluginFolder))
+            if (this is ICollectionFolder && this is not BasePluginFolder)
             {
                 var blockedMediaFolders = user.GetPreferenceValues<Guid>(PreferenceKind.BlockedMediaFolders);
                 if (blockedMediaFolders.Length > 0)
@@ -210,6 +260,7 @@ namespace MediaBrowser.Controller.Entities
         /// Loads our children.  Validation will occur externally.
         /// We want this synchronous.
         /// </summary>
+        /// <returns>Returns children.</returns>
         protected virtual List<BaseItem> LoadChildren()
         {
             // logger.LogDebug("Loading children from {0} {1} {2}", GetType().Name, Id, Path);
@@ -224,20 +275,20 @@ namespace MediaBrowser.Controller.Entities
 
         public Task ValidateChildren(IProgress<double> progress, CancellationToken cancellationToken)
         {
-            return ValidateChildren(progress, cancellationToken, new MetadataRefreshOptions(new DirectoryService(FileSystem)));
+            return ValidateChildren(progress, new MetadataRefreshOptions(new DirectoryService(FileSystem)), cancellationToken: cancellationToken);
         }
 
         /// <summary>
         /// Validates that the children of the folder still exist.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="metadataRefreshOptions">The metadata refresh options.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        public Task ValidateChildren(IProgress<double> progress, CancellationToken cancellationToken, MetadataRefreshOptions metadataRefreshOptions, bool recursive = true)
+        public Task ValidateChildren(IProgress<double> progress, MetadataRefreshOptions metadataRefreshOptions, bool recursive = true,  CancellationToken cancellationToken = default)
         {
-            return ValidateChildrenInternal(progress, cancellationToken, recursive, true, metadataRefreshOptions, metadataRefreshOptions.DirectoryService);
+            return ValidateChildrenInternal(progress, recursive, true, metadataRefreshOptions, metadataRefreshOptions.DirectoryService, cancellationToken);
         }
 
         private Dictionary<Guid, BaseItem> GetActualChildrenDictionary()
@@ -277,13 +328,13 @@ namespace MediaBrowser.Controller.Entities
         /// Validates the children internal.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
         /// <param name="refreshChildMetadata">if set to <c>true</c> [refresh child metadata].</param>
         /// <param name="refreshOptions">The refresh options.</param>
         /// <param name="directoryService">The directory service.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        protected virtual async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected virtual async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             if (recursive)
             {
@@ -292,7 +343,7 @@ namespace MediaBrowser.Controller.Entities
 
             try
             {
-                await ValidateChildrenInternal2(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService).ConfigureAwait(false);
+                await ValidateChildrenInternal2(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken).ConfigureAwait(false);
             }
             finally
             {
@@ -303,7 +354,7 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private async Task ValidateChildrenInternal2(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        private async Task ValidateChildrenInternal2(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             cancellationToken.ThrowIfCancellationRequested();
 
@@ -525,7 +576,7 @@ namespace MediaBrowser.Controller.Entities
         private Task ValidateSubFolders(IList<Folder> children, IDirectoryService directoryService, IProgress<double> progress, CancellationToken cancellationToken)
         {
             return RunTasks(
-                (folder, innerProgress) => folder.ValidateChildrenInternal(innerProgress, cancellationToken, true, false, null, directoryService),
+                (folder, innerProgress) => folder.ValidateChildrenInternal(innerProgress, true, false, null, directoryService, cancellationToken),
                 children,
                 progress,
                 cancellationToken);
@@ -594,6 +645,8 @@ namespace MediaBrowser.Controller.Entities
         /// Get the children of this folder from the actual file system.
         /// </summary>
         /// <returns>IEnumerable{BaseItem}.</returns>
+        /// <param name="directoryService">The directory service to use for operation.</param>
+        /// <returns>Returns set of base items.</returns>
         protected virtual IEnumerable<BaseItem> GetNonCachedChildren(IDirectoryService directoryService)
         {
             var collectionType = LibraryManager.GetContentType(this);
@@ -620,7 +673,7 @@ namespace MediaBrowser.Controller.Entities
         {
             if (LinkedChildren.Length > 0)
             {
-                if (!(this is ICollectionFolder))
+                if (this is not ICollectionFolder)
                 {
                     return GetChildren(user, true).Count;
                 }
@@ -677,7 +730,7 @@ namespace MediaBrowser.Controller.Entities
                 return PostFilterAndSort(items, query, true);
             }
 
-            if (!(this is UserRootFolder) && !(this is AggregateFolder) && query.ParentId == Guid.Empty)
+            if (this is not UserRootFolder && this is not AggregateFolder && query.ParentId == Guid.Empty)
             {
                 query.Parent = this;
             }
@@ -752,7 +805,7 @@ namespace MediaBrowser.Controller.Entities
         {
             if (LinkedChildren.Length > 0)
             {
-                if (!(this is ICollectionFolder))
+                if (this is not ICollectionFolder)
                 {
                     Logger.LogDebug("Query requires post-filtering due to LinkedChildren. Type: " + GetType().Name);
                     return true;
@@ -938,14 +991,18 @@ namespace MediaBrowser.Controller.Entities
             }
             else
             {
-                items = GetChildren(user, true).Where(filter);
+                // need to pass this param to the children.
+                var childQuery = new InternalItemsQuery
+                {
+                    DisplayAlbumFolders = query.DisplayAlbumFolders
+                };
+
+                items = GetChildren(user, true, childQuery).Where(filter);
             }
 
             return PostFilterAndSort(items, query, true);
         }
 
-        public static ICollectionManager CollectionManager { get; set; }
-
         protected QueryResult<BaseItem> PostFilterAndSort(IEnumerable<BaseItem> items, InternalItemsQuery query, bool enableSorting)
         {
             var user = query.User;
@@ -958,17 +1015,17 @@ namespace MediaBrowser.Controller.Entities
 
             if (!string.IsNullOrEmpty(query.NameStartsWithOrGreater))
             {
-                items = items.Where(i => string.Compare(query.NameStartsWithOrGreater, i.SortName, StringComparison.CurrentCultureIgnoreCase) < 1);
+                items = items.Where(i => string.Compare(query.NameStartsWithOrGreater, i.SortName, StringComparison.InvariantCultureIgnoreCase) < 1);
             }
 
             if (!string.IsNullOrEmpty(query.NameStartsWith))
             {
-                items = items.Where(i => i.SortName.StartsWith(query.NameStartsWith, StringComparison.OrdinalIgnoreCase));
+                items = items.Where(i => i.SortName.StartsWith(query.NameStartsWith, StringComparison.InvariantCultureIgnoreCase));
             }
 
             if (!string.IsNullOrEmpty(query.NameLessThan))
             {
-                items = items.Where(i => string.Compare(query.NameLessThan, i.SortName, StringComparison.CurrentCultureIgnoreCase) == 1);
+                items = items.Where(i => string.Compare(query.NameLessThan, i.SortName, StringComparison.InvariantCultureIgnoreCase) == 1);
             }
 
             // This must be the last filter
@@ -1274,10 +1331,23 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Adds the children to list.
         /// </summary>
-        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
         private void AddChildren(User user, bool includeLinkedChildren, Dictionary<Guid, BaseItem> result, bool recursive, InternalItemsQuery query)
         {
-            foreach (var child in GetEligibleChildrenForRecursiveChildren(user))
+            // If Query.AlbumFolders is set, then enforce the format as per the db in that it permits sub-folders in music albums.
+            IEnumerable<BaseItem> children = null;
+            if ((query?.DisplayAlbumFolders ?? false) && (this is MusicAlbum))
+            {
+                children = Children;
+                query = null;
+            }
+
+            // If there are not sub-folders, proceed as normal.
+            if (children == null)
+            {
+                children = GetEligibleChildrenForRecursiveChildren(user);
+            }
+
+            foreach (var child in children)
             {
                 bool? isVisibleToUser = null;
 
@@ -1317,18 +1387,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        /// <summary>
-        /// Gets allowed recursive children of an item.
-        /// </summary>
-        /// <param name="user">The user.</param>
-        /// <param name="includeLinkedChildren">if set to <c>true</c> [include linked children].</param>
-        /// <returns>IEnumerable{BaseItem}.</returns>
-        /// <exception cref="ArgumentNullException"></exception>
-        public IEnumerable<BaseItem> GetRecursiveChildren(User user, bool includeLinkedChildren = true)
-        {
-            return GetRecursiveChildren(user, null);
-        }
-
         public virtual IEnumerable<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
         {
             if (user == null)
@@ -1426,8 +1484,6 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
-        protected virtual bool FilterLinkedChildrenPerUser => false;
-
         public bool ContainsLinkedChildByItemId(Guid itemId)
         {
             var linkedChildren = LinkedChildren;
@@ -1489,7 +1545,7 @@ namespace MediaBrowser.Controller.Entities
 
                 var childOwner = child.GetOwner() ?? child;
 
-                if (childOwner != null && !(child is IItemByName))
+                if (child is not IItemByName)
                 {
                     var childProtocol = childOwner.PathProtocol;
                     if (!childProtocol.HasValue || childProtocol.Value != Model.MediaInfo.MediaProtocol.File)
@@ -1528,9 +1584,6 @@ namespace MediaBrowser.Controller.Entities
                 .Where(i => i.Item2 != null);
         }
 
-        [JsonIgnore]
-        protected override bool SupportsOwnedItems => base.SupportsOwnedItems || SupportsShortcutChildren;
-
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
             var changesFound = false;
@@ -1551,7 +1604,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Refreshes the linked children.
         /// </summary>
-        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
+        /// <param name="fileSystemChildren">The enumerable of file system metadata.</param>
+        /// <returns><c>true</c> if the linked children were updated, <c>false</c> otherwise.</returns>
         protected virtual bool RefreshLinkedChildren(IEnumerable<FileSystemMetadata> fileSystemChildren)
         {
             if (SupportsShortcutChildren)
@@ -1615,7 +1669,6 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="user">The user.</param>
         /// <param name="datePlayed">The date played.</param>
         /// <param name="resetPosition">if set to <c>true</c> [reset position].</param>
-        /// <returns>Task.</returns>
         public override void MarkPlayed(
             User user,
             DateTime? datePlayed,
@@ -1657,7 +1710,6 @@ namespace MediaBrowser.Controller.Entities
         /// Marks the unplayed.
         /// </summary>
         /// <param name="user">The user.</param>
-        /// <returns>Task.</returns>
         public override void MarkUnplayed(User user)
         {
             var itemsResult = GetItemList(new InternalItemsQuery
@@ -1694,51 +1746,6 @@ namespace MediaBrowser.Controller.Entities
             return !IsPlayed(user);
         }
 
-        [JsonIgnore]
-        public virtual bool SupportsUserDataFromChildren
-        {
-            get
-            {
-                // These are just far too slow.
-                if (this is ICollectionFolder)
-                {
-                    return false;
-                }
-
-                if (this is UserView)
-                {
-                    return false;
-                }
-
-                if (this is UserRootFolder)
-                {
-                    return false;
-                }
-
-                if (this is Channel)
-                {
-                    return false;
-                }
-
-                if (SourceType != SourceType.Library)
-                {
-                    return false;
-                }
-
-                var iItemByName = this as IItemByName;
-                if (iItemByName != null)
-                {
-                    var hasDualAccess = this as IHasDualAccess;
-                    if (hasDualAccess == null || hasDualAccess.IsAccessedByName)
-                    {
-                        return false;
-                    }
-                }
-
-                return true;
-            }
-        }
-
         public override void FillUserDataDtoValues(UserItemDataDto dto, UserItemData userData, BaseItemDto itemDto, User user, DtoOptions fields)
         {
             if (!SupportsUserDataFromChildren)
@@ -1768,20 +1775,15 @@ namespace MediaBrowser.Controller.Entities
                     {
                         EnableImages = false
                     }
-                });
+                }).TotalRecordCount;
 
-                double unplayedCount = unplayedQueryResult.TotalRecordCount;
+                dto.UnplayedItemCount = unplayedQueryResult;
 
-                dto.UnplayedItemCount = unplayedQueryResult.TotalRecordCount;
-
-                if (itemDto != null && itemDto.RecursiveItemCount.HasValue)
+                if (itemDto?.RecursiveItemCount > 0)
                 {
-                    if (itemDto.RecursiveItemCount.Value > 0)
-                    {
-                        var unplayedPercentage = (unplayedCount / itemDto.RecursiveItemCount.Value) * 100;
-                        dto.PlayedPercentage = 100 - unplayedPercentage;
-                        dto.Played = dto.PlayedPercentage.Value >= 100;
-                    }
+                    var unplayedPercentage = ((double)unplayedQueryResult / itemDto.RecursiveItemCount.Value) * 100;
+                    dto.PlayedPercentage = 100 - unplayedPercentage;
+                    dto.Played = dto.PlayedPercentage.Value >= 100;
                 }
                 else
                 {

MediaBrowser.Controller/Entities/Genre.cs

@@ -1,10 +1,12 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
+using Diacritics.Extensions;
 using MediaBrowser.Controller.Entities.Audio;
-using MediaBrowser.Controller.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities
@@ -14,6 +16,23 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Genre : BaseItem, IItemByName
     {
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override bool IsDisplayedAsFolder => true;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -32,20 +51,6 @@ namespace MediaBrowser.Controller.Entities
             return 1;
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
-        [JsonIgnore]
-        public override bool IsDisplayedAsFolder => true;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
@@ -70,9 +75,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -106,11 +108,13 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// This is called before any metadata refresh and returns true or false indicating if changes were made.
+        /// This is called before any metadata refresh and returns true if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Whether to replace all metadata.</param>
+        /// <returns>true if the item has change, else false.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))

MediaBrowser.Controller/Entities/ICollectionFolder.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 

MediaBrowser.Controller/Entities/IHasAspectRatio.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>

MediaBrowser.Controller/Entities/IHasDisplayOrder.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>

MediaBrowser.Controller/Entities/IHasMediaSources.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -18,6 +20,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the media sources.
         /// </summary>
+        /// <param name="enablePathSubstitution"><c>true</c> to enable path substitution, <c>false</c> to not.</param>
+        /// <returns>A list of media sources.</returns>
         List<MediaSourceInfo> GetMediaSources(bool enablePathSubstitution);
 
         List<MediaStream> GetMediaStreams();

MediaBrowser.Controller/Entities/IHasProgramAttributes.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using MediaBrowser.Model.LiveTv;

MediaBrowser.Controller/Entities/IHasScreenshots.cs

@@ -1,7 +1,7 @@
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
-    /// Interface IHasScreenshots.
+    /// The item has screenshots.
     /// </summary>
     public interface IHasScreenshots
     {

MediaBrowser.Controller/Entities/IHasSeries.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -7,7 +9,7 @@ namespace MediaBrowser.Controller.Entities
     public interface IHasSeries
     {
         /// <summary>
-        /// Gets the name of the series.
+        /// Gets or sets the name of the series.
         /// </summary>
         /// <value>The name of the series.</value>
         string SeriesName { get; set; }

MediaBrowser.Controller/Entities/IHasShares.cs

@@ -0,0 +1,11 @@
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
+
+namespace MediaBrowser.Controller.Entities
+{
+    public interface IHasShares
+    {
+        Share[] Shares { get; set; }
+    }
+}

MediaBrowser.Controller/Entities/IHasSpecialFeatures.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;

MediaBrowser.Controller/Entities/IHasTrailers.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -37,6 +39,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailer count.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{Guid}" />.</returns>
         public static int GetTrailerCount(this IHasTrailers item)
             => item.LocalTrailerIds.Count + item.RemoteTrailerIds.Count;
@@ -44,6 +47,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailer ids.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{Guid}" />.</returns>
         public static IReadOnlyList<Guid> GetTrailerIds(this IHasTrailers item)
         {
@@ -68,6 +72,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailers.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{BaseItem}" />.</returns>
         public static IReadOnlyList<BaseItem> GetTrailers(this IHasTrailers item)
         {

MediaBrowser.Controller/Entities/InternalItemsQuery.cs

@@ -1,4 +1,4 @@
-#pragma warning disable CS1591
+#pragma warning disable CA1044, CA1819, CA2227, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -12,15 +12,64 @@ namespace MediaBrowser.Controller.Entities
 {
     public class InternalItemsQuery
     {
+        public InternalItemsQuery()
+        {
+            AlbumArtistIds = Array.Empty<Guid>();
+            AlbumIds = Array.Empty<Guid>();
+            AncestorIds = Array.Empty<Guid>();
+            ArtistIds = Array.Empty<Guid>();
+            BlockUnratedItems = Array.Empty<UnratedItem>();
+            BoxSetLibraryFolders = Array.Empty<Guid>();
+            ChannelIds = Array.Empty<Guid>();
+            ContributingArtistIds = Array.Empty<Guid>();
+            DtoOptions = new DtoOptions();
+            EnableTotalRecordCount = true;
+            ExcludeArtistIds = Array.Empty<Guid>();
+            ExcludeInheritedTags = Array.Empty<string>();
+            ExcludeItemIds = Array.Empty<Guid>();
+            ExcludeItemTypes = Array.Empty<string>();
+            ExcludeTags = Array.Empty<string>();
+            GenreIds = Array.Empty<Guid>();
+            Genres = Array.Empty<string>();
+            GroupByPresentationUniqueKey = true;
+            ImageTypes = Array.Empty<ImageType>();
+            IncludeItemTypes = Array.Empty<string>();
+            ItemIds = Array.Empty<Guid>();
+            MediaTypes = Array.Empty<string>();
+            MinSimilarityScore = 20;
+            OfficialRatings = Array.Empty<string>();
+            OrderBy = Array.Empty<ValueTuple<string, SortOrder>>();
+            PersonIds = Array.Empty<Guid>();
+            PersonTypes = Array.Empty<string>();
+            PresetViews = Array.Empty<string>();
+            SeriesStatuses = Array.Empty<SeriesStatus>();
+            SourceTypes = Array.Empty<SourceType>();
+            StudioIds = Array.Empty<Guid>();
+            Tags = Array.Empty<string>();
+            TopParentIds = Array.Empty<Guid>();
+            TrailerTypes = Array.Empty<TrailerType>();
+            VideoTypes = Array.Empty<VideoType>();
+            Years = Array.Empty<int>();
+        }
+
+        public InternalItemsQuery(User? user)
+            : this()
+        {
+            if (user != null)
+            {
+                SetUser(user);
+            }
+        }
+
         public bool Recursive { get; set; }
 
         public int? StartIndex { get; set; }
 
         public int? Limit { get; set; }
 
-        public User User { get; set; }
+        public User? User { get; set; }
 
-        public BaseItem SimilarTo { get; set; }
+        public BaseItem? SimilarTo { get; set; }
 
         public bool? IsFolder { get; set; }
 
@@ -56,23 +105,23 @@ namespace MediaBrowser.Controller.Entities
 
         public bool? CollapseBoxSetItems { get; set; }
 
-        public string NameStartsWithOrGreater { get; set; }
+        public string? NameStartsWithOrGreater { get; set; }
 
-        public string NameStartsWith { get; set; }
+        public string? NameStartsWith { get; set; }
 
-        public string NameLessThan { get; set; }
+        public string? NameLessThan { get; set; }
 
-        public string NameContains { get; set; }
+        public string? NameContains { get; set; }
 
-        public string MinSortName { get; set; }
+        public string? MinSortName { get; set; }
 
-        public string PresentationUniqueKey { get; set; }
+        public string? PresentationUniqueKey { get; set; }
 
-        public string Path { get; set; }
+        public string? Path { get; set; }
 
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
-        public string Person { get; set; }
+        public string? Person { get; set; }
 
         public Guid[] PersonIds { get; set; }
 
@@ -80,7 +129,7 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid[] ExcludeItemIds { get; set; }
 
-        public string AdjacentTo { get; set; }
+        public string? AdjacentTo { get; set; }
 
         public string[] PersonTypes { get; set; }
 
@@ -180,29 +229,12 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid ParentId { get; set; }
 
-        public string ParentType { get; set; }
+        public string? ParentType { get; set; }
 
         public Guid[] AncestorIds { get; set; }
 
         public Guid[] TopParentIds { get; set; }
 
-        public BaseItem Parent
-        {
-            set
-            {
-                if (value == null)
-                {
-                    ParentId = Guid.Empty;
-                    ParentType = null;
-                }
-                else
-                {
-                    ParentId = value.Id;
-                    ParentType = value.GetType().Name;
-                }
-            }
-        }
-
         public string[] PresetViews { get; set; }
 
         public TrailerType[] TrailerTypes { get; set; }
@@ -211,9 +243,9 @@ namespace MediaBrowser.Controller.Entities
 
         public SeriesStatus[] SeriesStatuses { get; set; }
 
-        public string ExternalSeriesId { get; set; }
+        public string? ExternalSeriesId { get; set; }
 
-        public string ExternalId { get; set; }
+        public string? ExternalId { get; set; }
 
         public Guid[] AlbumIds { get; set; }
 
@@ -221,9 +253,9 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid[] ExcludeArtistIds { get; set; }
 
-        public string AncestorWithPresentationUniqueKey { get; set; }
+        public string? AncestorWithPresentationUniqueKey { get; set; }
 
-        public string SeriesPresentationUniqueKey { get; set; }
+        public string? SeriesPresentationUniqueKey { get; set; }
 
         public bool GroupByPresentationUniqueKey { get; set; }
 
@@ -233,7 +265,7 @@ namespace MediaBrowser.Controller.Entities
 
         public bool ForceDirect { get; set; }
 
-        public Dictionary<string, string> ExcludeProviderIds { get; set; }
+        public Dictionary<string, string>? ExcludeProviderIds { get; set; }
 
         public bool EnableGroupByMetadataKey { get; set; }
 
@@ -251,13 +283,13 @@ namespace MediaBrowser.Controller.Entities
 
         public int MinSimilarityScore { get; set; }
 
-        public string HasNoAudioTrackWithLanguage { get; set; }
+        public string? HasNoAudioTrackWithLanguage { get; set; }
 
-        public string HasNoInternalSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoInternalSubtitleTrackWithLanguage { get; set; }
 
-        public string HasNoExternalSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoExternalSubtitleTrackWithLanguage { get; set; }
 
-        public string HasNoSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoSubtitleTrackWithLanguage { get; set; }
 
         public bool? IsDeadArtist { get; set; }
 
@@ -265,74 +297,29 @@ namespace MediaBrowser.Controller.Entities
 
         public bool? IsDeadPerson { get; set; }
 
-        public InternalItemsQuery()
-        {
-            AlbumArtistIds = Array.Empty<Guid>();
-            AlbumIds = Array.Empty<Guid>();
-            AncestorIds = Array.Empty<Guid>();
-            ArtistIds = Array.Empty<Guid>();
-            BlockUnratedItems = Array.Empty<UnratedItem>();
-            BoxSetLibraryFolders = Array.Empty<Guid>();
-            ChannelIds = Array.Empty<Guid>();
-            ContributingArtistIds = Array.Empty<Guid>();
-            DtoOptions = new DtoOptions();
-            EnableTotalRecordCount = true;
-            ExcludeArtistIds = Array.Empty<Guid>();
-            ExcludeInheritedTags = Array.Empty<string>();
-            ExcludeItemIds = Array.Empty<Guid>();
-            ExcludeItemTypes = Array.Empty<string>();
-            ExcludeProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            ExcludeTags = Array.Empty<string>();
-            GenreIds = Array.Empty<Guid>();
-            Genres = Array.Empty<string>();
-            GroupByPresentationUniqueKey = true;
-            HasAnyProviderId = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            ImageTypes = Array.Empty<ImageType>();
-            IncludeItemTypes = Array.Empty<string>();
-            ItemIds = Array.Empty<Guid>();
-            MediaTypes = Array.Empty<string>();
-            MinSimilarityScore = 20;
-            OfficialRatings = Array.Empty<string>();
-            OrderBy = Array.Empty<ValueTuple<string, SortOrder>>();
-            PersonIds = Array.Empty<Guid>();
-            PersonTypes = Array.Empty<string>();
-            PresetViews = Array.Empty<string>();
-            SeriesStatuses = Array.Empty<SeriesStatus>();
-            SourceTypes = Array.Empty<SourceType>();
-            StudioIds = Array.Empty<Guid>();
-            Tags = Array.Empty<string>();
-            TopParentIds = Array.Empty<Guid>();
-            TrailerTypes = Array.Empty<TrailerType>();
-            VideoTypes = Array.Empty<VideoType>();
-            Years = Array.Empty<int>();
-        }
+        /// <summary>
+        /// Gets or sets a value indicating whether album sub-folders should be returned if they exist.
+        /// </summary>
+        public bool? DisplayAlbumFolders { get; set; }
 
-        public InternalItemsQuery(User user)
-            : this()
+        public BaseItem? Parent
         {
-            SetUser(user);
-        }
-
-        public void SetUser(User user)
-        {
-            if (user != null)
+            set
             {
-                MaxParentalRating = user.MaxParentalAgeRating;
-
-                if (MaxParentalRating.HasValue)
+                if (value == null)
                 {
-                    BlockUnratedItems = user.GetPreference(PreferenceKind.BlockUnratedItems)
-                        .Where(i => i != UnratedItem.Other.ToString())
-                        .Select(e => Enum.Parse<UnratedItem>(e, true)).ToArray();
+                    ParentId = Guid.Empty;
+                    ParentType = null;
+                }
+                else
+                {
+                    ParentId = value.Id;
+                    ParentType = value.GetType().Name;
                 }
-
-                ExcludeInheritedTags = user.GetPreference(PreferenceKind.BlockedTags);
-
-                User = user;
             }
         }
 
-        public Dictionary<string, string> HasAnyProviderId { get; set; }
+        public Dictionary<string, string>? HasAnyProviderId { get; set; }
 
         public Guid[] AlbumArtistIds { get; set; }
 
@@ -354,8 +341,25 @@ namespace MediaBrowser.Controller.Entities
 
         public int? MinWidth { get; set; }
 
-        public string SearchTerm { get; set; }
+        public string? SearchTerm { get; set; }
 
-        public string SeriesTimerId { get; set; }
+        public string? SeriesTimerId { get; set; }
+
+        public void SetUser(User user)
+        {
+            MaxParentalRating = user.MaxParentalAgeRating;
+
+            if (MaxParentalRating.HasValue)
+            {
+                string other = UnratedItem.Other.ToString();
+                BlockUnratedItems = user.GetPreference(PreferenceKind.BlockUnratedItems)
+                    .Where(i => i != other)
+                    .Select(e => Enum.Parse<UnratedItem>(e, true)).ToArray();
+            }
+
+            ExcludeInheritedTags = user.GetPreference(PreferenceKind.BlockedTags);
+
+            User = user;
+        }
     }
 }

MediaBrowser.Controller/Entities/InternalPeopleQuery.cs

@@ -1,12 +1,26 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
+using System.Collections.Generic;
 using Jellyfin.Data.Entities;
 
 namespace MediaBrowser.Controller.Entities
 {
     public class InternalPeopleQuery
     {
+        public InternalPeopleQuery()
+         : this(Array.Empty<string>(), Array.Empty<string>())
+        {
+        }
+
+        public InternalPeopleQuery(IReadOnlyList<string> personTypes, IReadOnlyList<string> excludePersonTypes)
+        {
+            PersonTypes = personTypes;
+            ExcludePersonTypes = excludePersonTypes;
+        }
+
         /// <summary>
         /// Gets or sets the maximum number of items the query should return.
         /// </summary>
@@ -14,9 +28,9 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid ItemId { get; set; }
 
-        public string[] PersonTypes { get; set; }
+        public IReadOnlyList<string> PersonTypes { get; }
 
-        public string[] ExcludePersonTypes { get; set; }
+        public IReadOnlyList<string> ExcludePersonTypes { get; }
 
         public int? MaxListOrder { get; set; }
 
@@ -27,11 +41,5 @@ namespace MediaBrowser.Controller.Entities
         public User User { get; set; }
 
         public bool? IsFavorite { get; set; }
-
-        public InternalPeopleQuery()
-        {
-            PersonTypes = Array.Empty<string>();
-            ExcludePersonTypes = Array.Empty<string>();
-        }
     }
 }

MediaBrowser.Controller/Entities/ItemImageInfo.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;

MediaBrowser.Controller/Entities/LinkedChild.cs

@@ -1,15 +1,20 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
-using System.Collections.Generic;
 using System.Globalization;
 using System.Text.Json.Serialization;
-using MediaBrowser.Model.IO;
 
 namespace MediaBrowser.Controller.Entities
 {
     public class LinkedChild
     {
+        public LinkedChild()
+        {
+            Id = Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture);
+        }
+
         public string Path { get; set; }
 
         public LinkedChildType Type { get; set; }
@@ -20,7 +25,7 @@ namespace MediaBrowser.Controller.Entities
         public string Id { get; set; }
 
         /// <summary>
-        /// Serves as a cache.
+        /// Gets or sets the linked item id.
         /// </summary>
         public Guid? ItemId { get; set; }
 
@@ -39,41 +44,5 @@ namespace MediaBrowser.Controller.Entities
 
             return child;
         }
-
-        public LinkedChild()
-        {
-            Id = Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture);
-        }
-    }
-
-    public enum LinkedChildType
-    {
-        Manual = 0,
-        Shortcut = 1
-    }
-
-    public class LinkedChildComparer : IEqualityComparer<LinkedChild>
-    {
-        private readonly IFileSystem _fileSystem;
-
-        public LinkedChildComparer(IFileSystem fileSystem)
-        {
-            _fileSystem = fileSystem;
-        }
-
-        public bool Equals(LinkedChild x, LinkedChild y)
-        {
-            if (x.Type == y.Type)
-            {
-                return _fileSystem.AreEqual(x.Path, y.Path);
-            }
-
-            return false;
-        }
-
-        public int GetHashCode(LinkedChild obj)
-        {
-            return ((obj.Path ?? string.Empty) + (obj.LibraryItemId ?? string.Empty) + obj.Type).GetHashCode();
-        }
     }
 }

MediaBrowser.Controller/Entities/LinkedChildComparer.cs

@@ -0,0 +1,35 @@
+#nullable disable
+
+#pragma warning disable CS1591
+
+using System;
+using System.Collections.Generic;
+using MediaBrowser.Model.IO;
+
+namespace MediaBrowser.Controller.Entities
+{
+    public class LinkedChildComparer : IEqualityComparer<LinkedChild>
+    {
+        private readonly IFileSystem _fileSystem;
+
+        public LinkedChildComparer(IFileSystem fileSystem)
+        {
+            _fileSystem = fileSystem;
+        }
+
+        public bool Equals(LinkedChild x, LinkedChild y)
+        {
+            if (x.Type == y.Type)
+            {
+                return _fileSystem.AreEqual(x.Path, y.Path);
+            }
+
+            return false;
+        }
+
+        public int GetHashCode(LinkedChild obj)
+        {
+            return ((obj.Path ?? string.Empty) + (obj.LibraryItemId ?? string.Empty) + obj.Type).GetHashCode(StringComparison.Ordinal);
+        }
+    }
+}

MediaBrowser.Controller/Entities/LinkedChildType.cs

@@ -0,0 +1,18 @@
+namespace MediaBrowser.Controller.Entities
+{
+    /// <summary>
+    /// The linked child type.
+    /// </summary>
+    public enum LinkedChildType
+    {
+        /// <summary>
+        /// Manually linked child.
+        /// </summary>
+        Manual = 0,
+
+        /// <summary>
+        /// Shortcut linked child.
+        /// </summary>
+        Shortcut = 1
+    }
+}

MediaBrowser.Controller/Entities/Movies/BoxSet.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1721, CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -47,6 +49,30 @@ namespace MediaBrowser.Controller.Entities.Movies
         /// <value>The display order.</value>
         public string DisplayOrder { get; set; }
 
+        [JsonIgnore]
+        private bool IsLegacyBoxSet
+        {
+            get
+            {
+                if (string.IsNullOrEmpty(Path))
+                {
+                    return false;
+                }
+
+                if (LinkedChildren.Length > 0)
+                {
+                    return false;
+                }
+
+                return !FileSystem.ContainsSubPath(ConfigurationManager.ApplicationPaths.DataPath, Path);
+            }
+        }
+
+        [JsonIgnore]
+        public override bool IsPreSorted => true;
+
+        public Guid[] LibraryFolderIds { get; set; }
+
         protected override bool GetBlockUnratedValue(User user)
         {
             return user.GetPreferenceValues<UnratedItem>(PreferenceKind.BlockUnratedItems).Contains(UnratedItem.Movie);
@@ -81,28 +107,6 @@ namespace MediaBrowser.Controller.Entities.Movies
             return new List<BaseItem>();
         }
 
-        [JsonIgnore]
-        private bool IsLegacyBoxSet
-        {
-            get
-            {
-                if (string.IsNullOrEmpty(Path))
-                {
-                    return false;
-                }
-
-                if (LinkedChildren.Length > 0)
-                {
-                    return false;
-                }
-
-                return !FileSystem.ContainsSubPath(ConfigurationManager.ApplicationPaths.DataPath, Path);
-            }
-        }
-
-        [JsonIgnore]
-        public override bool IsPreSorted => true;
-
         public override bool IsAuthorizedToDelete(User user, List<Folder> allCollectionFolders)
         {
             return true;
@@ -189,8 +193,6 @@ namespace MediaBrowser.Controller.Entities.Movies
             return IsVisible(user);
         }
 
-        public Guid[] LibraryFolderIds { get; set; }
-
         private Guid[] GetLibraryFolderIds(User user)
         {
             return LibraryManager.GetUserRootFolder().GetChildren(user, true)
@@ -217,8 +219,7 @@ namespace MediaBrowser.Controller.Entities.Movies
 
         private IEnumerable<BaseItem> FlattenItems(BaseItem item, List<Guid> expandedFolders)
         {
-            var boxset = item as BoxSet;
-            if (boxset != null)
+            if (item is BoxSet boxset)
             {
                 if (!expandedFolders.Contains(item.Id))
                 {

MediaBrowser.Controller/Entities/Movies/Movie.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -142,9 +144,9 @@ namespace MediaBrowser.Controller.Entities.Movies
         }
 
         /// <inheritdoc />
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {

MediaBrowser.Controller/Entities/MusicVideo.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -11,15 +13,15 @@ namespace MediaBrowser.Controller.Entities
 {
     public class MusicVideo : Video, IHasArtist, IHasMusicGenres, IHasLookupInfo<MusicVideoInfo>
     {
-        /// <inheritdoc />
-        [JsonIgnore]
-        public IReadOnlyList<string> Artists { get; set; }
-
         public MusicVideo()
         {
             Artists = Array.Empty<string>();
         }
 
+        /// <inheritdoc />
+        [JsonIgnore]
+        public IReadOnlyList<string> Artists { get; set; }
+
         public override UnratedItem GetBlockUnratedType()
         {
             return UnratedItem.Music;
@@ -34,9 +36,9 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {

MediaBrowser.Controller/Entities/PeopleHelper.cs

@@ -100,23 +100,5 @@ namespace MediaBrowser.Controller.Entities
                 existing.SetProviderId(id.Key, id.Value);
             }
         }
-
-        public static bool ContainsPerson(List<PersonInfo> people, string name)
-        {
-            if (string.IsNullOrEmpty(name))
-            {
-                throw new ArgumentNullException(nameof(name));
-            }
-
-            foreach (var i in people)
-            {
-                if (string.Equals(i.Name, name, StringComparison.OrdinalIgnoreCase))
-                {
-                    return true;
-                }
-            }
-
-            return false;
-        }
     }
 }

MediaBrowser.Controller/Entities/Person.cs

@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using MediaBrowser.Controller.Providers;
 using Microsoft.Extensions.Logging;
 
@@ -14,6 +16,26 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Person : BaseItem, IItemByName, IHasLookupInfo<PersonLookupInfo>
     {
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        /// <summary>
+        /// Gets a value indicating whether to enable alpha numeric sorting.
+        /// </summary>
+        [JsonIgnore]
+        public override bool EnableAlphaNumericSorting => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -47,14 +69,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
         public override bool CanDelete()
         {
             return false;
@@ -65,15 +79,6 @@ namespace MediaBrowser.Controller.Entities
             return true;
         }
 
-        [JsonIgnore]
-        public override bool EnableAlphaNumericSorting => false;
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -124,9 +129,11 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata"><c>true</c> to replace all metadata, <c>false</c> to not.</param>
+        /// <returns><c>true</c> if changes were made, <c>false</c> if not.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))

MediaBrowser.Controller/Entities/PersonInfo.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA2227, CS1591
 
 using System;
 using System.Collections.Generic;

MediaBrowser.Controller/Entities/Photo.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Text.Json.Serialization;
@@ -24,8 +26,7 @@ namespace MediaBrowser.Controller.Entities
                 var parents = GetParents();
                 foreach (var parent in parents)
                 {
-                    var photoAlbum = parent as PhotoAlbum;
-                    if (photoAlbum != null)
+                    if (parent is PhotoAlbum photoAlbum)
                     {
                         return photoAlbum;
                     }
@@ -35,6 +36,30 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
+        public string CameraMake { get; set; }
+
+        public string CameraModel { get; set; }
+
+        public string Software { get; set; }
+
+        public double? ExposureTime { get; set; }
+
+        public double? FocalLength { get; set; }
+
+        public ImageOrientation? Orientation { get; set; }
+
+        public double? Aperture { get; set; }
+
+        public double? ShutterSpeed { get; set; }
+
+        public double? Latitude { get; set; }
+
+        public double? Longitude { get; set; }
+
+        public double? Altitude { get; set; }
+
+        public int? IsoSpeedRating { get; set; }
+
         public override bool CanDownload()
         {
             return true;
@@ -68,29 +93,5 @@ namespace MediaBrowser.Controller.Entities
 
             return base.GetDefaultPrimaryImageAspectRatio();
         }
-
-        public string CameraMake { get; set; }
-
-        public string CameraModel { get; set; }
-
-        public string Software { get; set; }
-
-        public double? ExposureTime { get; set; }
-
-        public double? FocalLength { get; set; }
-
-        public ImageOrientation? Orientation { get; set; }
-
-        public double? Aperture { get; set; }
-
-        public double? ShutterSpeed { get; set; }
-
-        public double? Latitude { get; set; }
-
-        public double? Longitude { get; set; }
-
-        public double? Altitude { get; set; }
-
-        public int? IsoSpeedRating { get; set; }
     }
 }

MediaBrowser.Controller/Entities/Share.cs

@@ -1,12 +1,9 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Controller.Entities
 {
-    public interface IHasShares
-    {
-        Share[] Shares { get; set; }
-    }
-
     public class Share
     {
         public string UserId { get; set; }

MediaBrowser.Controller/Entities/Studio.cs

@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities
@@ -13,6 +15,23 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Studio : BaseItem, IItemByName
     {
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override bool IsDisplayedAsFolder => true;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -26,20 +45,6 @@ namespace MediaBrowser.Controller.Entities
             return GetUserDataKeys()[0];
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
-        [JsonIgnore]
-        public override bool IsDisplayedAsFolder => true;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 16;
@@ -65,9 +70,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -103,9 +105,11 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata"><c>true</c> to replace all metadata, <c>false</c> to not.</param>
+        /// <returns><c>true</c> if changes were made, <c>false</c> if not.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))

MediaBrowser.Controller/Entities/TV/Episode.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -32,7 +34,7 @@ namespace MediaBrowser.Controller.Entities.TV
         public IReadOnlyList<Guid> RemoteTrailerIds { get; set; }
 
         /// <summary>
-        /// Gets the season in which it aired.
+        /// Gets or sets the season in which it aired.
         /// </summary>
         /// <value>The aired season.</value>
         public int? AirsBeforeSeasonNumber { get; set; }
@@ -42,17 +44,11 @@ namespace MediaBrowser.Controller.Entities.TV
         public int? AirsBeforeEpisodeNumber { get; set; }
 
         /// <summary>
-        /// This is the ending episode number for double episodes.
+        /// Gets or sets the ending episode number for double episodes.
         /// </summary>
         /// <value>The index number.</value>
         public int? IndexNumberEnd { get; set; }
 
-        public string FindSeriesSortName()
-        {
-            var series = Series;
-            return series == null ? SeriesName : series.SortName;
-        }
-
         [JsonIgnore]
         protected override bool SupportsOwnedItems => IsStacked || MediaSourceCount > 1;
 
@@ -74,47 +70,8 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         protected override bool EnableDefaultVideoUserDataKeys => false;
 
-        public override double GetDefaultPrimaryImageAspectRatio()
-        {
-            // hack for tv plugins
-            if (SourceType == SourceType.Channel)
-            {
-                return 0;
-            }
-
-            return 16.0 / 9;
-        }
-
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
-
-            var series = Series;
-            if (series != null && ParentIndexNumber.HasValue && IndexNumber.HasValue)
-            {
-                var seriesUserDataKeys = series.GetUserDataKeys();
-                var take = seriesUserDataKeys.Count;
-                if (seriesUserDataKeys.Count > 1)
-                {
-                    take--;
-                }
-
-                var newList = seriesUserDataKeys.GetRange(0, take);
-                var suffix = ParentIndexNumber.Value.ToString("000", CultureInfo.InvariantCulture) + IndexNumber.Value.ToString("000", CultureInfo.InvariantCulture);
-                for (int i = 0; i < take; i++)
-                {
-                    newList[i] = newList[i] + suffix;
-                }
-
-                newList.AddRange(list);
-                list = newList;
-            }
-
-            return list;
-        }
-
         /// <summary>
-        /// This Episode's Series Instance.
+        /// Gets the Episode's Series Instance.
         /// </summary>
         /// <value>The series.</value>
         [JsonIgnore]
@@ -159,6 +116,74 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         public string SeasonName { get; set; }
 
+        [JsonIgnore]
+        public override bool SupportsRemoteImageDownloading
+        {
+            get
+            {
+                if (IsMissingEpisode)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+        }
+
+        [JsonIgnore]
+        public bool IsMissingEpisode => LocationType == LocationType.Virtual;
+
+        [JsonIgnore]
+        public Guid SeasonId { get; set; }
+
+        [JsonIgnore]
+        public Guid SeriesId { get; set; }
+
+        public string FindSeriesSortName()
+        {
+            var series = Series;
+            return series == null ? SeriesName : series.SortName;
+        }
+
+        public override double GetDefaultPrimaryImageAspectRatio()
+        {
+            // hack for tv plugins
+            if (SourceType == SourceType.Channel)
+            {
+                return 0;
+            }
+
+            return 16.0 / 9;
+        }
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            var series = Series;
+            if (series != null && ParentIndexNumber.HasValue && IndexNumber.HasValue)
+            {
+                var seriesUserDataKeys = series.GetUserDataKeys();
+                var take = seriesUserDataKeys.Count;
+                if (seriesUserDataKeys.Count > 1)
+                {
+                    take--;
+                }
+
+                var newList = seriesUserDataKeys.GetRange(0, take);
+                var suffix = ParentIndexNumber.Value.ToString("000", CultureInfo.InvariantCulture) + IndexNumber.Value.ToString("000", CultureInfo.InvariantCulture);
+                for (int i = 0; i < take; i++)
+                {
+                    newList[i] = newList[i] + suffix;
+                }
+
+                newList.AddRange(list);
+                list = newList;
+            }
+
+            return list;
+        }
+
         public string FindSeriesPresentationUniqueKey()
         {
             var series = Series;
@@ -216,8 +241,8 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("000 - ") : "")
-                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ") : "") + Name;
+            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("000 - ", CultureInfo.InvariantCulture) : string.Empty)
+                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty) + Name;
         }
 
         /// <summary>
@@ -240,28 +265,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return false;
         }
 
-        [JsonIgnore]
-        public override bool SupportsRemoteImageDownloading
-        {
-            get
-            {
-                if (IsMissingEpisode)
-                {
-                    return false;
-                }
-
-                return true;
-            }
-        }
-
-        [JsonIgnore]
-        public bool IsMissingEpisode => LocationType == LocationType.Virtual;
-
-        [JsonIgnore]
-        public Guid SeasonId { get; set; }
-        [JsonIgnore]
-        public Guid SeriesId { get; set; }
-
         public Guid FindSeriesId()
         {
             var series = FindParent<Series>();
@@ -284,7 +287,8 @@ namespace MediaBrowser.Controller.Entities.TV
 
         public override IEnumerable<FileSystemMetadata> GetDeletePaths()
         {
-            return new[] {
+            return new[]
+            {
                 new FileSystemMetadata
                 {
                     FullName = Path,
@@ -316,9 +320,9 @@ namespace MediaBrowser.Controller.Entities.TV
             return id;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!IsLocked)
             {
@@ -326,7 +330,7 @@ namespace MediaBrowser.Controller.Entities.TV
                 {
                     try
                     {
-                        if (LibraryManager.FillMissingEpisodeNumbersFromPath(this, replaceAllMetdata))
+                        if (LibraryManager.FillMissingEpisodeNumbersFromPath(this, replaceAllMetadata))
                         {
                             hasChanges = true;
                         }

MediaBrowser.Controller/Entities/TV/Season.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -36,6 +38,50 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         public override Guid DisplayParentId => SeriesId;
 
+        /// <summary>
+        /// Gets this Episode's Series Instance.
+        /// </summary>
+        /// <value>The series.</value>
+        [JsonIgnore]
+        public Series Series
+        {
+            get
+            {
+                var seriesId = SeriesId;
+                if (seriesId == Guid.Empty)
+                {
+                    seriesId = FindSeriesId();
+                }
+
+                return seriesId == Guid.Empty ? null : (LibraryManager.GetItemById(seriesId) as Series);
+            }
+        }
+
+        [JsonIgnore]
+        public string SeriesPath
+        {
+            get
+            {
+                var series = Series;
+
+                if (series != null)
+                {
+                    return series.Path;
+                }
+
+                return System.IO.Path.GetDirectoryName(Path);
+            }
+        }
+
+        [JsonIgnore]
+        public string SeriesPresentationUniqueKey { get; set; }
+
+        [JsonIgnore]
+        public string SeriesName { get; set; }
+
+        [JsonIgnore]
+        public Guid SeriesId { get; set; }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -78,41 +124,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return result;
         }
 
-        /// <summary>
-        /// This Episode's Series Instance.
-        /// </summary>
-        /// <value>The series.</value>
-        [JsonIgnore]
-        public Series Series
-        {
-            get
-            {
-                var seriesId = SeriesId;
-                if (seriesId == Guid.Empty)
-                {
-                    seriesId = FindSeriesId();
-                }
-
-                return seriesId == Guid.Empty ? null : (LibraryManager.GetItemById(seriesId) as Series);
-            }
-        }
-
-        [JsonIgnore]
-        public string SeriesPath
-        {
-            get
-            {
-                var series = Series;
-
-                if (series != null)
-                {
-                    return series.Path;
-                }
-
-                return System.IO.Path.GetDirectoryName(Path);
-            }
-        }
-
         public override string CreatePresentationUniqueKey()
         {
             if (IndexNumber.HasValue)
@@ -120,7 +131,7 @@ namespace MediaBrowser.Controller.Entities.TV
                 var series = Series;
                 if (series != null)
                 {
-                    return series.PresentationUniqueKey + "-" + (IndexNumber ?? 0).ToString("000");
+                    return series.PresentationUniqueKey + "-" + (IndexNumber ?? 0).ToString("000", CultureInfo.InvariantCulture);
                 }
             }
 
@@ -133,7 +144,7 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return IndexNumber != null ? IndexNumber.Value.ToString("0000") : Name;
+            return IndexNumber != null ? IndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) : Name;
         }
 
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
@@ -155,6 +166,9 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Gets the episodes.
         /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="options">The options to use.</param>
+        /// <returns>Set of episodes.</returns>
         public List<BaseItem> GetEpisodes(User user, DtoOptions options)
         {
             return GetEpisodes(Series, user, options);
@@ -191,15 +205,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return UnratedItem.Series;
         }
 
-        [JsonIgnore]
-        public string SeriesPresentationUniqueKey { get; set; }
-
-        [JsonIgnore]
-        public string SeriesName { get; set; }
-
-        [JsonIgnore]
-        public Guid SeriesId { get; set; }
-
         public string FindSeriesPresentationUniqueKey()
         {
             var series = Series;
@@ -239,10 +244,11 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
+        /// <param name="replaceAllMetadata"><c>true</c> to replace metdata, <c>false</c> to not.</param>
         /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!IndexNumber.HasValue && !string.IsNullOrEmpty(Path))
             {

MediaBrowser.Controller/Entities/TV/Series.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -57,8 +59,11 @@ namespace MediaBrowser.Controller.Entities.TV
         public IReadOnlyList<Guid> RemoteTrailerIds { get; set; }
 
         /// <summary>
-        /// airdate, dvd or absolute.
+        /// Gets or sets the display order.
         /// </summary>
+        /// <remarks>
+        /// Valid options are airdate, dvd or absolute.
+        /// </remarks>
         public string DisplayOrder { get; set; }
 
         /// <summary>
@@ -67,6 +72,9 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <value>The status.</value>
         public SeriesStatus? Status { get; set; }
 
+        [JsonIgnore]
+        public override bool StopRefreshIfLocalMetadataFound => false;
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -288,7 +296,7 @@ namespace MediaBrowser.Controller.Entities.TV
             // Refresh seasons
             foreach (var item in items)
             {
-                if (!(item is Season))
+                if (item is not Season)
                 {
                     continue;
                 }
@@ -316,20 +324,13 @@ namespace MediaBrowser.Controller.Entities.TV
 
                 cancellationToken.ThrowIfCancellationRequested();
 
-                var skipItem = false;
-
-                var episode = item as Episode;
-
-                if (episode != null
+                bool skipItem = item is Episode episode
                     && refreshOptions.MetadataRefreshMode != MetadataRefreshMode.FullRefresh
                     && !refreshOptions.ReplaceAllMetadata
                     && episode.IsMissingEpisode
                     && episode.LocationType == LocationType.Virtual
                     && episode.PremiereDate.HasValue
-                    && (DateTime.UtcNow - episode.PremiereDate.Value).TotalDays > 30)
-                {
-                    skipItem = true;
-                }
+                    && (DateTime.UtcNow - episode.PremiereDate.Value).TotalDays > 30;
 
                 if (!skipItem)
                 {
@@ -396,6 +397,10 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Filters the episodes by season.
         /// </summary>
+        /// <param name="episodes">The episodes.</param>
+        /// <param name="parentSeason">The season.</param>
+        /// <param name="includeSpecials"><c>true</c> to include special, <c>false</c> to not.</param>
+        /// <returns>The set of episodes.</returns>
         public static IEnumerable<BaseItem> FilterEpisodesBySeason(IEnumerable<BaseItem> episodes, Season parentSeason, bool includeSpecials)
         {
             var seasonNumber = parentSeason.IndexNumber;
@@ -426,6 +431,10 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Filters the episodes by season.
         /// </summary>
+        /// <param name="episodes">The episodes.</param>
+        /// <param name="seasonNumber">The season.</param>
+        /// <param name="includeSpecials"><c>true</c> to include special, <c>false</c> to not.</param>
+        /// <returns>The set of episodes.</returns>
         public static IEnumerable<Episode> FilterEpisodesBySeason(IEnumerable<Episode> episodes, int seasonNumber, bool includeSpecials)
         {
             if (!includeSpecials || seasonNumber < 1)
@@ -501,8 +510,5 @@ namespace MediaBrowser.Controller.Entities.TV
 
             return list;
         }
-
-        [JsonIgnore]
-        public override bool StopRefreshIfLocalMetadataFound => false;
     }
 }

MediaBrowser.Controller/Entities/Trailer.cs

@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -21,6 +23,9 @@ namespace MediaBrowser.Controller.Entities
             TrailerTypes = Array.Empty<TrailerType>();
         }
 
+        [JsonIgnore]
+        public override bool StopRefreshIfLocalMetadataFound => false;
+
         public TrailerType[] TrailerTypes { get; set; }
 
         public override double GetDefaultPrimaryImageAspectRatio()
@@ -43,9 +48,9 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {
@@ -95,8 +100,5 @@ namespace MediaBrowser.Controller.Entities
 
             return list;
         }
-
-        [JsonIgnore]
-        public override bool StopRefreshIfLocalMetadataFound => false;
     }
 }

MediaBrowser.Controller/Entities/UserItemData.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -10,6 +12,13 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class UserItemData
     {
+        public const double MinLikeValue = 6.5;
+
+        /// <summary>
+        /// The _rating.
+        /// </summary>
+        private double? _rating;
+
         /// <summary>
         /// Gets or sets the user id.
         /// </summary>
@@ -22,11 +31,6 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The key.</value>
         public string Key { get; set; }
 
-        /// <summary>
-        /// The _rating.
-        /// </summary>
-        private double? _rating;
-
         /// <summary>
         /// Gets or sets the users 0-10 rating.
         /// </summary>
@@ -91,10 +95,8 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The index of the subtitle stream.</value>
         public int? SubtitleStreamIndex { get; set; }
 
-        public const double MinLikeValue = 6.5;
-
         /// <summary>
-        /// This is an interpreted property to indicate likes or dislikes
+        /// Gets or sets a value indicating whether the item is liked or not.
         /// This should never be serialized.
         /// </summary>
         /// <value><c>null</c> if [likes] contains no value, <c>true</c> if [likes]; otherwise, <c>false</c>.</value>

MediaBrowser.Controller/Entities/UserRootFolder.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -19,8 +21,37 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class UserRootFolder : Folder
     {
-        private List<Guid> _childrenIds = null;
         private readonly object _childIdsLock = new object();
+        private List<Guid> _childrenIds = null;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UserRootFolder"/> class.
+        /// </summary>
+        public UserRootFolder()
+        {
+            IsRoot = true;
+        }
+
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        [JsonIgnore]
+        protected override bool SupportsShortcutChildren => true;
+
+        [JsonIgnore]
+        public override bool IsPreSorted => true;
+
+        private void ClearCache()
+        {
+            lock (_childIdsLock)
+            {
+                _childrenIds = null;
+            }
+        }
+
         protected override List<BaseItem> LoadChildren()
         {
             lock (_childIdsLock)
@@ -36,20 +67,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
-
-        private void ClearCache()
-        {
-            lock (_childIdsLock)
-            {
-                _childrenIds = null;
-            }
-        }
-
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
         {
             if (query.Recursive)
@@ -71,12 +88,6 @@ namespace MediaBrowser.Controller.Entities
             return GetChildren(user, true).Count;
         }
 
-        [JsonIgnore]
-        protected override bool SupportsShortcutChildren => true;
-
-        [JsonIgnore]
-        public override bool IsPreSorted => true;
-
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             var list = base.GetEligibleChildrenForRecursiveChildren(user).ToList();
@@ -85,10 +96,10 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
             ClearCache();
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (string.Equals("default", Name, StringComparison.OrdinalIgnoreCase))
             {
@@ -106,11 +117,11 @@ namespace MediaBrowser.Controller.Entities
             return base.GetNonCachedChildren(directoryService);
         }
 
-        protected override async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             ClearCache();
 
-            await base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService)
+            await base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken)
                 .ConfigureAwait(false);
 
             ClearCache();

MediaBrowser.Controller/Entities/UserView.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -13,21 +15,56 @@ namespace MediaBrowser.Controller.Entities
 {
     public class UserView : Folder, IHasCollectionType
     {
-        /// <inheritdoc />
+        private static readonly string[] _viewTypesEligibleForGrouping = new string[]
+        {
+            Model.Entities.CollectionType.Movies,
+            Model.Entities.CollectionType.TvShows,
+            string.Empty
+        };
+
+        private static readonly string[] _originalFolderViewTypes = new string[]
+        {
+            Model.Entities.CollectionType.Books,
+            Model.Entities.CollectionType.MusicVideos,
+            Model.Entities.CollectionType.HomeVideos,
+            Model.Entities.CollectionType.Photos,
+            Model.Entities.CollectionType.Music,
+            Model.Entities.CollectionType.BoxSets
+        };
+
+        public static ITVSeriesManager TVSeriesManager { get; set; }
+
+        /// <summary>
+        /// Gets or sets the view type.
+        /// </summary>
         public string ViewType { get; set; }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Gets or sets the display parent id.
+        /// </summary>
         public new Guid DisplayParentId { get; set; }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Gets or sets the user id.
+        /// </summary>
         public Guid? UserId { get; set; }
 
-        public static ITVSeriesManager TVSeriesManager;
-
         /// <inheritdoc />
         [JsonIgnore]
         public string CollectionType => ViewType;
 
+        /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         /// <inheritdoc />
         public override IEnumerable<Guid> GetIdsForAncestorQuery()
         {
@@ -45,17 +82,13 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
-
+        /// <inheritdoc />
         public override int GetChildCount(User user)
         {
             return GetChildren(user, true).Count;
         }
 
+        /// <inheritdoc />
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
         {
             var parent = this as Folder;
@@ -73,12 +106,10 @@ namespace MediaBrowser.Controller.Entities
                 .GetUserItems(parent, this, CollectionType, query);
         }
 
+        /// <inheritdoc />
         public override List<BaseItem> GetChildren(User user, bool includeLinkedChildren, InternalItemsQuery query)
         {
-            if (query == null)
-            {
-                query = new InternalItemsQuery(user);
-            }
+            query ??= new InternalItemsQuery(user);
 
             query.EnableTotalRecordCount = false;
             var result = GetItemList(query);
@@ -86,16 +117,19 @@ namespace MediaBrowser.Controller.Entities
             return result.ToList();
         }
 
+        /// <inheritdoc />
         public override bool CanDelete()
         {
             return false;
         }
 
+        /// <inheritdoc />
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
         }
 
+        /// <inheritdoc />
         public override IEnumerable<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
         {
             query.SetUser(user);
@@ -106,32 +140,26 @@ namespace MediaBrowser.Controller.Entities
             return GetItemList(query);
         }
 
+        /// <inheritdoc />
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             return GetChildren(user, false);
         }
 
-        private static string[] UserSpecificViewTypes = new string[]
-            {
-                Model.Entities.CollectionType.Playlists
-            };
-
         public static bool IsUserSpecific(Folder folder)
         {
-            var collectionFolder = folder as ICollectionFolder;
-
-            if (collectionFolder == null)
+            if (folder is not ICollectionFolder collectionFolder)
             {
                 return false;
             }
 
-            var supportsUserSpecific = folder as ISupportsUserSpecificView;
-            if (supportsUserSpecific != null && supportsUserSpecific.EnableUserSpecificView)
+            if (folder is ISupportsUserSpecificView supportsUserSpecific
+                && supportsUserSpecific.EnableUserSpecificView)
             {
                 return true;
             }
 
-            return UserSpecificViewTypes.Contains(collectionFolder.CollectionType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return string.Equals(Model.Entities.CollectionType.Playlists, collectionFolder.CollectionType, StringComparison.OrdinalIgnoreCase);
         }
 
         public static bool IsEligibleForGrouping(Folder folder)
@@ -140,39 +168,19 @@ namespace MediaBrowser.Controller.Entities
                     && IsEligibleForGrouping(collectionFolder.CollectionType);
         }
 
-        private static string[] ViewTypesEligibleForGrouping = new string[]
-            {
-                Model.Entities.CollectionType.Movies,
-                Model.Entities.CollectionType.TvShows,
-                string.Empty
-            };
-
         public static bool IsEligibleForGrouping(string viewType)
         {
-            return ViewTypesEligibleForGrouping.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return _viewTypesEligibleForGrouping.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
         }
 
-        private static string[] OriginalFolderViewTypes = new string[]
-            {
-                Model.Entities.CollectionType.Books,
-                Model.Entities.CollectionType.MusicVideos,
-                Model.Entities.CollectionType.HomeVideos,
-                Model.Entities.CollectionType.Photos,
-                Model.Entities.CollectionType.Music,
-                Model.Entities.CollectionType.BoxSets
-            };
-
         public static bool EnableOriginalFolder(string viewType)
         {
-            return OriginalFolderViewTypes.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return _originalFolderViewTypes.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
         }
 
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, System.Threading.CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, Providers.MetadataRefreshOptions refreshOptions, Providers.IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, Providers.MetadataRefreshOptions refreshOptions, Providers.IDirectoryService directoryService, System.Threading.CancellationToken cancellationToken)
         {
             return Task.CompletedTask;
         }
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }

MediaBrowser.Controller/Entities/UserViewBuilder.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -53,17 +55,17 @@ namespace MediaBrowser.Controller.Entities
             // if (query.IncludeItemTypes != null &&
             //    query.IncludeItemTypes.Length == 1 &&
             //    string.Equals(query.IncludeItemTypes[0], "Playlist", StringComparison.OrdinalIgnoreCase))
-            //{
+            // {
             //    if (!string.Equals(viewType, CollectionType.Playlists, StringComparison.OrdinalIgnoreCase))
             //    {
             //        return await FindPlaylists(queryParent, user, query).ConfigureAwait(false);
             //    }
-            //}
+            // }
 
             switch (viewType)
             {
                 case CollectionType.Folders:
-                    return GetResult(_libraryManager.GetUserRootFolder().GetChildren(user, true), queryParent, query);
+                    return GetResult(_libraryManager.GetUserRootFolder().GetChildren(user, true), query);
 
                 case CollectionType.TvShows:
                     return GetTvView(queryParent, user, query);
@@ -108,7 +110,7 @@ namespace MediaBrowser.Controller.Entities
                     return GetMovieMovies(queryParent, user, query);
 
                 case SpecialFolder.MovieCollections:
-                    return GetMovieCollections(queryParent, user, query);
+                    return GetMovieCollections(user, query);
 
                 case SpecialFolder.TvFavoriteEpisodes:
                     return GetFavoriteEpisodes(queryParent, user, query);
@@ -120,7 +122,7 @@ namespace MediaBrowser.Controller.Entities
                     {
                         if (queryParent is UserView)
                         {
-                            return GetResult(GetMediaFolders(user).OfType<Folder>().SelectMany(i => i.GetChildren(user, true)), queryParent, query);
+                            return GetResult(GetMediaFolders(user).OfType<Folder>().SelectMany(i => i.GetChildren(user, true)), query);
                         }
 
                         return queryParent.GetItems(query);
@@ -158,7 +160,7 @@ namespace MediaBrowser.Controller.Entities
                 GetUserView(SpecialFolder.MovieGenres, "Genres", "5", parent)
             };
 
-            return GetResult(list, parent, query);
+            return GetResult(list, query);
         }
 
         private QueryResult<BaseItem> GetFavoriteMovies(Folder parent, User user, InternalItemsQuery query)
@@ -205,7 +207,7 @@ namespace MediaBrowser.Controller.Entities
             return _libraryManager.GetItemsResult(query);
         }
 
-        private QueryResult<BaseItem> GetMovieCollections(Folder parent, User user, InternalItemsQuery query)
+        private QueryResult<BaseItem> GetMovieCollections(User user, InternalItemsQuery query)
         {
             query.Parent = null;
             query.IncludeItemTypes = new[] { nameof(BoxSet) };
@@ -273,9 +275,9 @@ namespace MediaBrowser.Controller.Entities
                     }
                 })
                 .Where(i => i != null)
-                .Select(i => GetUserViewWithName(i.Name, SpecialFolder.MovieGenre, i.SortName, parent));
+                .Select(i => GetUserViewWithName(SpecialFolder.MovieGenre, i.SortName, parent));
 
-            return GetResult(genres, parent, query);
+            return GetResult(genres, query);
         }
 
         private QueryResult<BaseItem> GetMovieGenreItems(Folder queryParent, Folder displayParent, User user, InternalItemsQuery query)
@@ -321,7 +323,7 @@ namespace MediaBrowser.Controller.Entities
                 GetUserView(SpecialFolder.TvGenres, "Genres", "6", parent)
             };
 
-            return GetResult(list, parent, query);
+            return GetResult(list, query);
         }
 
         private QueryResult<BaseItem> GetTvLatest(Folder parent, User user, InternalItemsQuery query)
@@ -342,12 +344,14 @@ namespace MediaBrowser.Controller.Entities
             var parentFolders = GetMediaFolders(parent, query.User, new[] { CollectionType.TvShows, string.Empty });
 
             var result = _tvSeriesManager.GetNextUp(
-            new NextUpQuery
-            {
-                Limit = query.Limit,
-                StartIndex = query.StartIndex,
-                UserId = query.User.Id
-            }, parentFolders, query.DtoOptions);
+                new NextUpQuery
+                {
+                    Limit = query.Limit,
+                    StartIndex = query.StartIndex,
+                    UserId = query.User.Id
+                },
+                parentFolders,
+                query.DtoOptions);
 
             return result;
         }
@@ -399,9 +403,9 @@ namespace MediaBrowser.Controller.Entities
                     }
                 })
                 .Where(i => i != null)
-                .Select(i => GetUserViewWithName(i.Name, SpecialFolder.TvGenre, i.SortName, parent));
+                .Select(i => GetUserViewWithName(SpecialFolder.TvGenre, i.SortName, parent));
 
-            return GetResult(genres, parent, query);
+            return GetResult(genres, query);
         }
 
         private QueryResult<BaseItem> GetTvGenreItems(Folder queryParent, Folder displayParent, User user, InternalItemsQuery query)
@@ -428,13 +432,12 @@ namespace MediaBrowser.Controller.Entities
 
         private QueryResult<BaseItem> GetResult<T>(
             IEnumerable<T> items,
-            BaseItem queryParent,
             InternalItemsQuery query)
             where T : BaseItem
         {
             items = items.Where(i => Filter(i, query.User, query, _userDataManager, _libraryManager));
 
-            return PostFilterAndSort(items, queryParent, null, query, _libraryManager, _config);
+            return PostFilterAndSort(items, null, query, _libraryManager);
         }
 
         public static bool FilterItem(BaseItem item, InternalItemsQuery query)
@@ -444,11 +447,9 @@ namespace MediaBrowser.Controller.Entities
 
         public static QueryResult<BaseItem> PostFilterAndSort(
             IEnumerable<BaseItem> items,
-            BaseItem queryParent,
             int? totalRecordLimit,
             InternalItemsQuery query,
-            ILibraryManager libraryManager,
-            IServerConfigurationManager configurationManager)
+            ILibraryManager libraryManager)
         {
             var user = query.User;
 
@@ -997,7 +998,7 @@ namespace MediaBrowser.Controller.Entities
             return new BaseItem[] { parent };
         }
 
-        private UserView GetUserViewWithName(string name, string type, string sortName, BaseItem parent)
+        private UserView GetUserViewWithName(string type, string sortName, BaseItem parent)
         {
             return _userViewManager.GetUserSubView(parent.Id, parent.Id.ToString("N", CultureInfo.InvariantCulture), type, sortName);
         }

MediaBrowser.Controller/Entities/Video.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -26,6 +28,14 @@ namespace MediaBrowser.Controller.Entities
         ISupportsPlaceHolders,
         IHasMediaSources
     {
+        public Video()
+        {
+            AdditionalParts = Array.Empty<string>();
+            LocalAlternateVersions = Array.Empty<string>();
+            SubtitleFiles = Array.Empty<string>();
+            LinkedAlternateVersions = Array.Empty<LinkedChild>();
+        }
+
         [JsonIgnore]
         public string PrimaryVersionId { get; set; }
 
@@ -72,30 +82,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        public void SetPrimaryVersionId(string id)
-        {
-            if (string.IsNullOrEmpty(id))
-            {
-                PrimaryVersionId = null;
-            }
-            else
-            {
-                PrimaryVersionId = id;
-            }
-
-            PresentationUniqueKey = CreatePresentationUniqueKey();
-        }
-
-        public override string CreatePresentationUniqueKey()
-        {
-            if (!string.IsNullOrEmpty(PrimaryVersionId))
-            {
-                return PrimaryVersionId;
-            }
-
-            return base.CreatePresentationUniqueKey();
-        }
-
         [JsonIgnore]
         public override bool SupportsThemeMedia => true;
 
@@ -149,24 +135,6 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The aspect ratio.</value>
         public string AspectRatio { get; set; }
 
-        public Video()
-        {
-            AdditionalParts = Array.Empty<string>();
-            LocalAlternateVersions = Array.Empty<string>();
-            SubtitleFiles = Array.Empty<string>();
-            LinkedAlternateVersions = Array.Empty<LinkedChild>();
-        }
-
-        public override bool CanDownload()
-        {
-            if (VideoType == VideoType.Dvd || VideoType == VideoType.BluRay)
-            {
-                return false;
-            }
-
-            return IsFileProtocol;
-        }
-
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
 
@@ -194,16 +162,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public override bool HasLocalAlternateVersions => LocalAlternateVersions.Length > 0;
 
-        public IEnumerable<Guid> GetAdditionalPartIds()
-        {
-            return AdditionalParts.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
-        }
-
-        public IEnumerable<Guid> GetLocalAlternateVersionIds()
-        {
-            return LocalAlternateVersions.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
-        }
-
         public static ILiveTvManager LiveTvManager { get; set; }
 
         [JsonIgnore]
@@ -220,21 +178,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        protected override bool IsActiveRecording()
-        {
-            return LiveTvManager.GetActiveRecordingInfo(Path) != null;
-        }
-
-        public override bool CanDelete()
-        {
-            if (IsActiveRecording())
-            {
-                return false;
-            }
-
-            return base.CanDelete();
-        }
-
         [JsonIgnore]
         public bool IsCompleteMedia
         {
@@ -252,80 +195,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         protected virtual bool EnableDefaultVideoUserDataKeys => true;
 
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
-
-            if (EnableDefaultVideoUserDataKeys)
-            {
-                if (ExtraType.HasValue)
-                {
-                    var key = this.GetProviderId(MetadataProvider.Tmdb);
-                    if (!string.IsNullOrEmpty(key))
-                    {
-                        list.Insert(0, GetUserDataKey(key));
-                    }
-
-                    key = this.GetProviderId(MetadataProvider.Imdb);
-                    if (!string.IsNullOrEmpty(key))
-                    {
-                        list.Insert(0, GetUserDataKey(key));
-                    }
-                }
-                else
-                {
-                    var key = this.GetProviderId(MetadataProvider.Imdb);
-                    if (!string.IsNullOrEmpty(key))
-                    {
-                        list.Insert(0, key);
-                    }
-
-                    key = this.GetProviderId(MetadataProvider.Tmdb);
-                    if (!string.IsNullOrEmpty(key))
-                    {
-                        list.Insert(0, key);
-                    }
-                }
-            }
-
-            return list;
-        }
-
-        private string GetUserDataKey(string providerId)
-        {
-            var key = providerId + "-" + ExtraType.ToString().ToLowerInvariant();
-
-            // Make sure different trailers have their own data.
-            if (RunTimeTicks.HasValue)
-            {
-                key += "-" + RunTimeTicks.Value.ToString(CultureInfo.InvariantCulture);
-            }
-
-            return key;
-        }
-
-        public IEnumerable<Video> GetLinkedAlternateVersions()
-        {
-            return LinkedAlternateVersions
-                .Select(GetLinkedChild)
-                .Where(i => i != null)
-                .OfType<Video>()
-                .OrderBy(i => i.SortName);
-        }
-
-        /// <summary>
-        /// Gets the additional parts.
-        /// </summary>
-        /// <returns>IEnumerable{Video}.</returns>
-        public IOrderedEnumerable<Video> GetAdditionalParts()
-        {
-            return GetAdditionalPartIds()
-                .Select(i => LibraryManager.GetItemById(i))
-                .Where(i => i != null)
-                .OfType<Video>()
-                .OrderBy(i => i.SortName);
-        }
-
         [JsonIgnore]
         public override string ContainingFolderPath
         {
@@ -367,6 +236,153 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
+        /// <summary>
+        /// Gets a value indicating whether [is3 D].
+        /// </summary>
+        /// <value><c>true</c> if [is3 D]; otherwise, <c>false</c>.</value>
+        [JsonIgnore]
+        public bool Is3D => Video3DFormat.HasValue;
+
+        /// <summary>
+        /// Gets the type of the media.
+        /// </summary>
+        /// <value>The type of the media.</value>
+        [JsonIgnore]
+        public override string MediaType => Model.Entities.MediaType.Video;
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            if (EnableDefaultVideoUserDataKeys)
+            {
+                if (ExtraType.HasValue)
+                {
+                    var key = this.GetProviderId(MetadataProvider.Tmdb);
+                    if (!string.IsNullOrEmpty(key))
+                    {
+                        list.Insert(0, GetUserDataKey(key));
+                    }
+
+                    key = this.GetProviderId(MetadataProvider.Imdb);
+                    if (!string.IsNullOrEmpty(key))
+                    {
+                        list.Insert(0, GetUserDataKey(key));
+                    }
+                }
+                else
+                {
+                    var key = this.GetProviderId(MetadataProvider.Imdb);
+                    if (!string.IsNullOrEmpty(key))
+                    {
+                        list.Insert(0, key);
+                    }
+
+                    key = this.GetProviderId(MetadataProvider.Tmdb);
+                    if (!string.IsNullOrEmpty(key))
+                    {
+                        list.Insert(0, key);
+                    }
+                }
+            }
+
+            return list;
+        }
+
+        public void SetPrimaryVersionId(string id)
+        {
+            if (string.IsNullOrEmpty(id))
+            {
+                PrimaryVersionId = null;
+            }
+            else
+            {
+                PrimaryVersionId = id;
+            }
+
+            PresentationUniqueKey = CreatePresentationUniqueKey();
+        }
+
+        public override string CreatePresentationUniqueKey()
+        {
+            if (!string.IsNullOrEmpty(PrimaryVersionId))
+            {
+                return PrimaryVersionId;
+            }
+
+            return base.CreatePresentationUniqueKey();
+        }
+
+        public override bool CanDownload()
+        {
+            if (VideoType == VideoType.Dvd || VideoType == VideoType.BluRay)
+            {
+                return false;
+            }
+
+            return IsFileProtocol;
+        }
+
+        protected override bool IsActiveRecording()
+        {
+            return LiveTvManager.GetActiveRecordingInfo(Path) != null;
+        }
+
+        public override bool CanDelete()
+        {
+            if (IsActiveRecording())
+            {
+                return false;
+            }
+
+            return base.CanDelete();
+        }
+
+        public IEnumerable<Guid> GetAdditionalPartIds()
+        {
+            return AdditionalParts.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
+        }
+
+        public IEnumerable<Guid> GetLocalAlternateVersionIds()
+        {
+            return LocalAlternateVersions.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
+        }
+
+        private string GetUserDataKey(string providerId)
+        {
+            var key = providerId + "-" + ExtraType.ToString().ToLowerInvariant();
+
+            // Make sure different trailers have their own data.
+            if (RunTimeTicks.HasValue)
+            {
+                key += "-" + RunTimeTicks.Value.ToString(CultureInfo.InvariantCulture);
+            }
+
+            return key;
+        }
+
+        public IEnumerable<Video> GetLinkedAlternateVersions()
+        {
+            return LinkedAlternateVersions
+                .Select(GetLinkedChild)
+                .Where(i => i != null)
+                .OfType<Video>()
+                .OrderBy(i => i.SortName);
+        }
+
+        /// <summary>
+        /// Gets the additional parts.
+        /// </summary>
+        /// <returns>IEnumerable{Video}.</returns>
+        public IOrderedEnumerable<Video> GetAdditionalParts()
+        {
+            return GetAdditionalPartIds()
+                .Select(i => LibraryManager.GetItemById(i))
+                .Where(i => i != null)
+                .OfType<Video>()
+                .OrderBy(i => i.SortName);
+        }
+
         internal override ItemUpdateType UpdateFromResolvedItem(BaseItem newItem)
         {
             var updateType = base.UpdateFromResolvedItem(newItem);
@@ -395,20 +411,6 @@ namespace MediaBrowser.Controller.Entities
             return updateType;
         }
 
-        /// <summary>
-        /// Gets a value indicating whether [is3 D].
-        /// </summary>
-        /// <value><c>true</c> if [is3 D]; otherwise, <c>false</c>.</value>
-        [JsonIgnore]
-        public bool Is3D => Video3DFormat.HasValue;
-
-        /// <summary>
-        /// Gets the type of the media.
-        /// </summary>
-        /// <value>The type of the media.</value>
-        [JsonIgnore]
-        public override string MediaType => Model.Entities.MediaType.Video;
-
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
             var hasChanges = await base.RefreshedOwnedItems(options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
@@ -480,7 +482,8 @@ namespace MediaBrowser.Controller.Entities
         {
             if (!IsInMixedFolder)
             {
-                return new[] {
+                return new[]
+                {
                     new FileSystemMetadata
                     {
                         FullName = ContainingFolderPath,

MediaBrowser.Controller/Entities/Year.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -13,6 +15,25 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Year : BaseItem, IItemByName
     {
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        public override bool CanDelete()
+        {
+            return false;
+        }
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -21,14 +42,6 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -37,14 +50,6 @@ namespace MediaBrowser.Controller.Entities
             return value;
         }
 
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
-        public override bool CanDelete()
-        {
-            return false;
-        }
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
@@ -52,9 +57,7 @@ namespace MediaBrowser.Controller.Entities
 
         public IList<BaseItem> GetTaggedItems(InternalItemsQuery query)
         {
-            var usCulture = new CultureInfo("en-US");
-
-            if (!int.TryParse(Name, NumberStyles.Integer, usCulture, out var year))
+            if (!int.TryParse(Name, NumberStyles.Integer, CultureInfo.InvariantCulture, out var year))
             {
                 return new List<BaseItem>();
             }
@@ -74,9 +77,6 @@ namespace MediaBrowser.Controller.Entities
             return null;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -110,11 +110,13 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// This is called before any metadata refresh and returns true or false indicating if changes were made.
+        /// This is called before any metadata refresh and returns true if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Whether to replace all metadata.</param>
+        /// <returns>true if the item has change, else false.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))

MediaBrowser.Controller/Events/IEventConsumer.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Threading.Tasks;
 
 namespace MediaBrowser.Controller.Events

MediaBrowser.Controller/Events/IEventManager.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Threading.Tasks;
 
 namespace MediaBrowser.Controller.Events

MediaBrowser.Controller/Events/Session/SessionEndedEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Controller.Session;
 
 namespace MediaBrowser.Controller.Events.Session

MediaBrowser.Controller/Events/Session/SessionStartedEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Controller.Session;
 
 namespace MediaBrowser.Controller.Events.Session

MediaBrowser.Controller/Events/Updates/PluginInstallationCancelledEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Model.Updates;
 
 namespace MediaBrowser.Controller.Events.Updates

MediaBrowser.Controller/Events/Updates/PluginInstalledEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Model.Updates;
 
 namespace MediaBrowser.Controller.Events.Updates

MediaBrowser.Controller/Events/Updates/PluginInstallingEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Model.Updates;
 
 namespace MediaBrowser.Controller.Events.Updates

MediaBrowser.Controller/Events/Updates/PluginUpdatedEventArgs.cs

@@ -1,4 +1,4 @@
-using Jellyfin.Data.Events;
+using Jellyfin.Data.Events;
 using MediaBrowser.Model.Updates;
 
 namespace MediaBrowser.Controller.Events.Updates

MediaBrowser.Controller/Extensions/StringExtensions.cs

@@ -1,53 +0,0 @@
-#nullable enable
-#pragma warning disable CS1591
-
-using System;
-using System.Globalization;
-using System.Linq;
-using System.Text;
-using System.Text.RegularExpressions;
-
-namespace MediaBrowser.Controller.Extensions
-{
-    /// <summary>
-    /// Class BaseExtensions.
-    /// </summary>
-    public static class StringExtensions
-    {
-        public static string RemoveDiacritics(this string text)
-        {
-            var chars = Normalize(text, NormalizationForm.FormD)
-                .Where(ch => CharUnicodeInfo.GetUnicodeCategory(ch) != UnicodeCategory.NonSpacingMark);
-
-            return Normalize(string.Concat(chars), NormalizationForm.FormC);
-        }
-
-        private static string Normalize(string text, NormalizationForm form, bool stripStringOnFailure = true)
-        {
-            if (stripStringOnFailure)
-            {
-                try
-                {
-                    return text.Normalize(form);
-                }
-                catch (ArgumentException)
-                {
-                    // will throw if input contains invalid unicode chars
-                    // https://mnaoumov.wordpress.com/2014/06/14/stripping-invalid-characters-from-utf-16-strings/
-                    text = Regex.Replace(text, "([\ud800-\udbff](?![\udc00-\udfff]))|((?<![\ud800-\udbff])[\udc00-\udfff])", "");
-                    return Normalize(text, form, false);
-                }
-            }
-
-            try
-            {
-                return text.Normalize(form);
-            }
-            catch (ArgumentException)
-            {
-                // if it still fails, return the original text
-                return text;
-            }
-        }
-    }
-}

MediaBrowser.Controller/IDisplayPreferencesManager.cs

@@ -1,3 +1,5 @@
+#nullable disable
+
 using System;
 using System.Collections.Generic;
 using Jellyfin.Data.Entities;

MediaBrowser.Controller/IO/FileData.cs

@@ -24,7 +24,7 @@ namespace MediaBrowser.Controller.IO
         /// <param name="flattenFolderDepth">The flatten folder depth.</param>
         /// <param name="resolveShortcuts">if set to <c>true</c> [resolve shortcuts].</param>
         /// <returns>Dictionary{System.StringFileSystemInfo}.</returns>
-        /// <exception cref="ArgumentNullException">path</exception>
+        /// <exception cref="ArgumentNullException"><paramref name="path" /> is <c>null</c> or empty.</exception>
         public static FileSystemMetadata[] GetFilteredFileSystemEntries(
             IDirectoryService directoryService,
             string path,