Removed 3rd-Party libraries.

MQTTnet.Core/Adapter/MqttChannelAdapterExtensions.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using MQTTnet.Core.Packets;
+
+namespace MQTTnet.Core.Adapter
+{
+    public static class MqttChannelAdapterExtensions
+    {
+        public static Task SendPacketsAsync(this IMqttChannelAdapter adapter, TimeSpan timeout, CancellationToken cancellationToken, params MqttBasePacket[] packets)
+        {
+            if (adapter == null) throw new ArgumentNullException(nameof(adapter));
+
+            return adapter.SendPacketsAsync(timeout, cancellationToken, packets);
+        }
+    }
+}