fixed build

Emby.Dlna/Main/DlnaEntryPoint.cs

@@ -316,7 +316,7 @@ namespace Emby.Dlna.Main
                 _logger.LogInformation("Registering publisher for {0} on {1}", fullService, address);
 
                 var uri = new UriBuilder(_appHost.GetSmartApiUrl(address.Address) + descriptorUri);
-                if (_appHost.PublishedServerUrl == null)
+                if (!string.IsNullOrEmpty(_appHost.PublishedServerUrl))
                 {
                     // DLNA will only work over http, so we must reset to http:// : {port}.
                     uri.Scheme = "http";

MediaBrowser.Controller/IServerApplicationHost.cs

@@ -55,7 +55,7 @@ namespace MediaBrowser.Controller
         /// <summary>
         /// Gets the configured published server url.
         /// </summary>
-        Uri PublishedServerUrl { get; }
+        string PublishedServerUrl { get; }
 
         /// <summary>
         /// Gets the system info.