add default forum layout support

src/Discord.Net.Core/Entities/Channels/ForumChannelProperties.cs

@@ -57,4 +57,9 @@ public class ForumChannelProperties : TextChannelProperties
     /// Gets or sets the rule used to order posts in forum channels.
     /// </summary>
     public Optional<ForumSortOrder> DefaultSortOrder { get; set; }
+
+    /// <summary>
+    /// Gets or sets the rule used to display posts in a forum channel.
+    /// </summary>
+    public Optional<ForumLayout> DefaultLayout { get; set; }
 }

src/Discord.Net.Core/Entities/Channels/ForumLayout.cs

@@ -0,0 +1,22 @@
+namespace Discord;
+
+/// <summary>
+///     Represents the layout type used to display posts in a forum channel.
+/// </summary>
+public enum ForumLayout
+{
+    /// <summary>
+    /// A preferred forum layout hasn't been set by a server admin
+    /// </summary>
+    Default = 0,
+
+    /// <summary>
+    /// List View: display forum posts in a text-focused list
+    /// </summary>
+    List = 1,
+
+    /// <summary>
+    /// Gallery View: display forum posts in a media-focused gallery
+    /// </summary>
+    Grid = 2
+}

src/Discord.Net.Core/Entities/Channels/IForumChannel.cs

@@ -63,13 +63,18 @@ namespace Discord
         IEmote DefaultReactionEmoji { get; }
 
         /// <summary>
-        /// Gets or sets the rule used to order posts in forum channels.
+        /// Gets the rule used to order posts in forum channels.
         /// </summary>
         /// <remarks>
         /// Defaults to null, which indicates a preferred sort order hasn't been set
         /// </remarks>
         ForumSortOrder? DefaultSortOrder { get; }
 
+        /// <summary>
+        /// Gets the rule used to display posts in a forum channel.
+        /// </summary>
+        ForumLayout DefaultLayout { get; }
+
         /// <summary>
         ///     Modifies this forum channel.
         /// </summary>

src/Discord.Net.Rest/API/Common/Channel.cs

@@ -89,5 +89,8 @@ namespace Discord.API
         [JsonProperty("default_reaction_emoji")]
         public Optional<ForumReactionEmoji> DefaultReactionEmoji { get; set; }
 
+        [JsonProperty("default_forum_layout")]
+        public Optional<ForumLayout> DefaultForumLayout { get; set; }
+
     }
 }

src/Discord.Net.Rest/API/Rest/ModifyForumChannelParams.cs

@@ -20,4 +20,7 @@ internal class ModifyForumChannelParams : ModifyTextChannelParams
 
     [JsonProperty("default_sort_order")]
     public Optional<ForumSortOrder> DefaultSortOrder { get; set; }
+
+    [JsonProperty("default_forum_layout")]
+    public Optional<ForumLayout> DefaultLayout { get; set; }
 }

src/Discord.Net.Rest/Entities/Channels/RestForumChannel.cs

@@ -41,6 +41,9 @@ namespace Discord.Rest
         /// <inheritdoc/>
         public ForumSortOrder? DefaultSortOrder { get; private set; }
 
+        /// <inheritdoc />
+        public ForumLayout DefaultLayout { get; private set; }
+
         /// <inheritdoc/>
         public string Mention => MentionUtils.MentionChannel(Id);
 
@@ -87,6 +90,7 @@ namespace Discord.Rest
             }
 
             CategoryId = model.CategoryId.GetValueOrDefault();
+            DefaultLayout= model.DefaultForumLayout.GetValueOrDefault();
         }
 
         /// <inheritdoc/>

src/Discord.Net.WebSocket/Entities/Channels/SocketForumChannel.cs

@@ -45,6 +45,9 @@ namespace Discord.WebSocket
         /// <inheritdoc/>
         public ForumSortOrder? DefaultSortOrder { get; private set; }
 
+        /// <inheritdoc />
+        public ForumLayout DefaultLayout { get; private set; }
+
         /// <summary>
         ///     Gets the parent (category) of this channel in the guild's channel list.
         /// </summary>
@@ -93,6 +96,8 @@ namespace Discord.WebSocket
             }
 
             CategoryId = model.CategoryId.GetValueOrDefault();
+
+            DefaultLayout = model.DefaultForumLayout.GetValueOrDefault();
         }
 
         /// <inheritdoc />