Fix build

Source/MQTTnet/Client/Options/MqttClientWebSocketOptions.cs

@@ -31,6 +31,7 @@ namespace MQTTnet.Client
         }
 
 #if !NETSTANDARD1_3
+#if !WINDOWS_UWP
         /// <summary>
         ///     Gets or sets the keep alive interval for the Web Socket connection.
         ///     This is not related to the keep alive interval for the MQTT protocol.
@@ -42,6 +43,13 @@ namespace MQTTnet.Client
         ///     This is not related to the credentials which are used for the MQTT protocol.
         /// </summary>
         public bool UseDefaultCredentials { get; set; }
+#else
+        /// <summary>
+        ///     Gets or sets the keep alive interval for the Web Socket connection.
+        ///     This is not related to the keep alive interval for the MQTT protocol.
+        /// </summary>
+        public TimeSpan KeepAliveInterval { get; set; } = TimeSpan.FromSeconds(30);
+#endif
 #endif
     }
 }
\ No newline at end of file

Source/MQTTnet/Implementations/MqttWebSocketChannel.cs

@@ -218,9 +218,11 @@ namespace MQTTnet.Implementations
 #endif
                 }
             }
-            
+
 #if !NETSTANDARD1_3
+#if !WINDOWS_UWP
             clientWebSocket.Options.UseDefaultCredentials = _options.UseDefaultCredentials;
+#endif
             clientWebSocket.Options.KeepAliveInterval = _options.KeepAliveInterval;
 #endif
             clientWebSocket.Options.Credentials = _options.Credentials;