Fix breaking changes.

MQTTnet.Core/Client/MqttClientSslOptions.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace MQTTnet.Core.Client
+{
+    public sealed class MqttClientSslOptions
+    {
+        public bool UseSsl { get; set; }
+
+        public bool CheckCertificateRevocation { get; set; }
+
+        public List<byte[]> Certificates { get; set; }
+    }
+}