Follow up from previous commit

src/Discord.Net.Net45/API/Client/Rest/BulkMessageDelete.cs

@@ -0,0 +1,23 @@
+using Newtonsoft.Json;
+ 
+ namespace Discord.API.Client.Rest
+ {
+     [JsonObject(MemberSerialization.OptIn)]
+     public class BulkMessageDelete : IRestRequest
+     {
+         string IRestRequest.Endpoint => $"/channels/{ChannelId}/messages/bulk_delete";
+         string IRestRequest.Method => "POST";
+         object IRestRequest.Payload => this;
+ 
+         public ulong ChannelId { get; set; }
+ 
+         public BulkMessageDelete(ulong channelId, ulong[] messageIds)
+         {
+             ChannelId = channelId;
+             MessageIds = messageIds;
+         }
+ 
+         [JsonProperty("messages")]
+         public ulong[] MessageIds { get; set; }
+     }
+ }