Fixed CreateGuildBan ignoring DeleteMessageDays, fixes #256

src/Discord.Net.Core/API/DiscordRestApiClient.cs

@@ -601,7 +601,7 @@ namespace Discord.API
             Preconditions.AtLeast(args.DeleteMessageDays, 0, nameof(args.DeleteMessageDays));
             options = RequestOptions.CreateOrClone(options);
 
-            await SendJsonAsync("PUT", $"guilds/{guildId}/bans/{userId}", args, options: options).ConfigureAwait(false);
+            await SendAsync("PUT", $"guilds/{guildId}/bans/{userId}?delete-message-days={args.DeleteMessageDays}", options: options).ConfigureAwait(false);
         }
         public async Task RemoveGuildBanAsync(ulong guildId, ulong userId, RequestOptions options = null)
         {

src/Discord.Net.Core/API/Rest/CreateGuildBanParams.cs

@@ -6,7 +6,6 @@ namespace Discord.API.Rest
     [JsonObject(MemberSerialization = MemberSerialization.OptIn)]
     public class CreateGuildBanParams
     {
-        [JsonProperty("delete-message-days")]
         public Optional<int> DeleteMessageDays { get; set; }
     }
 }