applied reviewer suggestions: removing unnecessary async and adding necessary async

Emby.Dlna/PlayTo/PlayToController.cs

@@ -890,9 +890,9 @@ namespace Emby.Dlna.PlayTo
         }
 
         /// <inheritdoc />
-        public async Task CloseAllWebSockets(CancellationToken cancellationToken)
+        public Task CloseAllWebSockets(CancellationToken cancellationToken)
         {
-            await Task.CompletedTask;
+            return Task.CompletedTask;
         }
 
         private class StreamParams

Emby.Server.Implementations/Session/SessionManager.cs

@@ -1359,13 +1359,13 @@ namespace Emby.Server.Implementations.Session
         /// </summary>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        public Task SendServerShutdownNotification(CancellationToken cancellationToken)
+        public async Task SendServerShutdownNotification(CancellationToken cancellationToken)
         {
             CheckDisposed();
 
-            CloseAllWebSockets(cancellationToken).ConfigureAwait(false);
+            await CloseAllWebSockets(cancellationToken).ConfigureAwait(false);
 
-            return SendMessageToSessions(Sessions, SessionMessageType.ServerShuttingDown, string.Empty, cancellationToken);
+            await SendMessageToSessions(Sessions, SessionMessageType.ServerShuttingDown, string.Empty, cancellationToken).ConfigureAwait(false);
         }
 
         /// <summary>