Merge pull request #4248 from crobibero/ws-document-filter

Manually register models used in websocket messages.

Jellyfin.Server/Extensions/ApiServiceCollectionExtensions.cs

@@ -263,6 +263,7 @@ namespace Jellyfin.Server.Extensions
                 c.AddSwaggerTypeMappings();
 
                 c.OperationFilter<FileResponseFilter>();
+                c.DocumentFilter<WebsocketModelFilter>();
             });
         }