Removed Message.Acknowledge

src/Discord.Net/Legacy.cs

@@ -169,12 +169,8 @@ namespace Discord.Legacy
             return channel.DownloadMessages(limit, relativeMessageId, relativeDir, useCache);
         }
 
-        [Obsolete("Use Message.Acknowledge")]
-        public static Task AckMessage(this DiscordClient client, Message message)
-        {
-            if (message == null) throw new ArgumentNullException(nameof(message));
-            return message.Acknowledge();
-        }
+        [Obsolete("Removed in 0.9a3", true)]
+        public static Task AckMessage(this DiscordClient client, Message message) => null;
 
         /*[Obsolete("Use Channel.ImportMessages")]
         public IEnumerable<Message> ImportMessages(Channel channel, string json)

src/Discord.Net/Models/Message.cs

@@ -325,14 +325,6 @@ namespace Discord
             try { await Client.ClientAPI.Send(request).ConfigureAwait(false); }
             catch (HttpException ex) when (ex.StatusCode == HttpStatusCode.NotFound) { }
         }
-        
-        public Task Acknowledge()
-        {
-            if (User.Id != Client.CurrentUser.Id)
-                return Client.ClientAPI.Send(new AckMessageRequest(Channel.Id, Id));
-            else
-                return TaskHelper.CompletedTask;
-        }
 
         /// <summary> Returns true if the logged-in user was mentioned. </summary>
         public bool IsMentioningMe(bool includeRoles = false)