public static Forum CreateInstance()
        {
            return TypeAccessor<Forum>.CreateInstance();
        }

       public Forum(IServiceProvider provider)
        {
            _serviceProvider = provider;
            _imageManager = ServiceProvider.GetRequiredService<IForumImageManager>();
        }

Janus\Janus\Features\ForumViewer\Export\MessageExporter.cs

emd.UnreadMessagesOnly
? activeMsgSvc.ActiveMessages
: activeMsgSvc.ActiveMessages.Where(msg => !msg.IsRead));

       public static Forum CreateInstance()
AN>         {
AN>             return TypeAccessor<Forum>.CreateInstance();
AN>         }
AN>

       public Forum(IServiceProvider provider)
AN>         {
AN>             _serviceProvider = provider;
AN>             _imageManager = ServiceProvider.GetRequiredService<IForumImageManager>();
AN>         }
AN>

        private static string BuildHTMLPage(IList<IMsg> msgs, ProgressDelegate progressDelegate, bool processSmiles)
        {
            TextFormatter formatter = new TextFormatter();
            StringBuilder stringBuilder = new StringBuilder();
            Forum forum = _activeForum;
            stringBuilder.AppendFormat(
...

       private static void Export2HTML(IList<IMsg> msgs, Stream stream, ProgressDelegate progressDelegate)
        {
            Encoding encoding = Encoding.GetEncoding(1251);

            using (StreamWriter streamWriter = new StreamWriter(stream, encoding))
            {
                string htmlPage = BuildHTMLPage(msgs, progressDelegate, false);
                streamWriter.Write(htmlPage);
            }
        }