Use event pattern correctly for incoming server connections.

MQTTnet.Core/Adapter/IMqttServerAdapter.cs

@@ -6,7 +6,7 @@ namespace MQTTnet.Core.Adapter
 {
     public interface IMqttServerAdapter
     {
-        event Action<IMqttCommunicationAdapter> ClientAccepted;
+        event EventHandler<MqttServerAdapterClientAcceptedEventArgs> ClientAccepted;
 
         Task StartAsync(MqttServerOptions options);
         Task StopAsync();

MQTTnet.Core/Adapter/MqttServerAdapterClientAcceptedEventArgs.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace MQTTnet.Core.Adapter
+{
+    public class MqttServerAdapterClientAcceptedEventArgs : EventArgs
+    {
+        public MqttServerAdapterClientAcceptedEventArgs(IMqttCommunicationAdapter client)
+        {
+            Client = client ?? throw new ArgumentNullException(nameof(client));
+        }
+
+        public IMqttCommunicationAdapter Client { get; }
+    }
+}

MQTTnet.Core/Server/MqttClientConnectedEventArgs.cs

@@ -1,7 +1,6 @@
-using MQTTnet.Core.Server;
-using System;
+using System;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Core.Server
 {
     public class MqttClientConnectedEventArgs : EventArgs
     {

MQTTnet.Core/Server/MqttClientDisconnectedEventArgs.cs

@@ -1,7 +1,6 @@
-using MQTTnet.Core.Server;
-using System;
+using System;
 
-namespace MQTTnet.Core.Adapter
+namespace MQTTnet.Core.Server
 {
     public class MqttClientDisconnectedEventArgs : EventArgs
     {

MQTTnet.Core/Server/MqttServer.cs

@@ -77,9 +77,9 @@ namespace MQTTnet.Core.Server
             MqttNetTrace.Information(nameof(MqttServer), "Stopped.");
         }
 
-        private void OnClientAccepted(IMqttCommunicationAdapter adapter)
+        private void OnClientAccepted(object sender, MqttServerAdapterClientAcceptedEventArgs eventArgs)
         {
-            Task.Run(() =>_clientSessionsManager.RunClientSessionAsync(adapter), _cancellationTokenSource.Token);
+            Task.Run(() =>_clientSessionsManager.RunClientSessionAsync(eventArgs.Client), _cancellationTokenSource.Token);
         }
 
         private void OnClientConnected(object sender, MqttClientConnectedEventArgs eventArgs)