Add missing overloads for client disconnect.

Add timeout for disconnect in managed client.

Source/MQTTnet.Extensions.ManagedClient/ManagedMqttClient.cs

@@ -292,7 +292,14 @@ namespace MQTTnet.Extensions.ManagedClient
                 {
                     try
                     {
-                        await InternalClient.DisconnectAsync().ConfigureAwait(false);
+                        using (var disconnectTimeout = new CancellationTokenSource(Options.ClientOptions.CommunicationTimeout))
+                        {
+                            await InternalClient.DisconnectAsync(disconnectTimeout.Token).ConfigureAwait(false);
+                        }
+                    }
+                    catch (OperationCanceledException)
+                    {
+                        _logger.Warning("Timeout while sending DISCONNECT packet.");
                     }
                     catch (Exception exception)
                     {

Source/MQTTnet/Client/Disconnecting/MqttClientDisconnectOptions.cs

@@ -1,6 +1,6 @@
 namespace MQTTnet.Client.Disconnecting
 {
-    public class MqttClientDisconnectOptions
+    public sealed class MqttClientDisconnectOptions
     {
         public MqttClientDisconnectReason ReasonCode { get; set; } = MqttClientDisconnectReason.NormalDisconnection;
 

Source/MQTTnet/Client/MqttClientExtensions.cs

@@ -128,7 +128,21 @@ namespace MQTTnet.Client
         {
             if (client == null) throw new ArgumentNullException(nameof(client));
 
-            return client.DisconnectAsync(new MqttClientDisconnectOptions());
+            return client.DisconnectAsync(CancellationToken.None);
+        }
+
+        public static Task DisconnectAsync(this IMqttClient client, MqttClientDisconnectOptions options)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
+            return client.DisconnectAsync(options, CancellationToken.None);
+        }
+
+        public static Task DisconnectAsync(this IMqttClient client, CancellationToken cancellationToken)
+        {
+            if (client == null) throw new ArgumentNullException(nameof(client));
+
+            return client.DisconnectAsync(new MqttClientDisconnectOptions(), cancellationToken);
         }
 
         public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient client, params MqttTopicFilter[] topicFilters)
@@ -176,13 +190,6 @@ namespace MQTTnet.Client
             return client.ConnectAsync(options, CancellationToken.None);
         }
 
-        public static Task DisconnectAsync(this IMqttClient client, MqttClientDisconnectOptions options)
-        {
-            if (client == null) throw new ArgumentNullException(nameof(client));
-
-            return client.DisconnectAsync(options, CancellationToken.None);
-        }
-
         public static Task SendExtendedAuthenticationExchangeDataAsync(this IMqttClient client, MqttExtendedAuthenticationExchangeData data)
         {
             if (client == null) throw new ArgumentNullException(nameof(client));

Source/MQTTnet/Diagnostics/MqttNetScopedLoggerExtensions.cs

@@ -19,6 +19,11 @@ namespace MQTTnet.Diagnostics
             logger.Publish(MqttNetLogLevel.Warning, message, parameters, exception);
         }
         
+        public static void Warning(this IMqttNetScopedLogger logger, string message, params object[] parameters)
+        {
+            logger.Publish(MqttNetLogLevel.Warning, message, parameters, null);
+        }
+
         public static void Error(this IMqttNetScopedLogger logger, Exception exception, string message, params object[] parameters)
         {
             logger.Publish(MqttNetLogLevel.Error, message, parameters, exception);