Fix license header

Change-Id: I4f91be6d0e9d706c00ad5907c54c56e39292a95d

client/src/main/java/com/vaadin/client/ui/UnknownExtensionConnector.java

@@ -1,12 +1,12 @@
 /*
- * Copyright 2000-2014 Vaadin Ltd.
- * 
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
@@ -21,7 +21,7 @@ import com.vaadin.client.extensions.AbstractExtensionConnector;
 /**
  * Connector used as a placeholder for extensions that are not present in the
  * widgetset.
- * 
+ *
  * @since 7.7.4
  * @author Vaadin Ltd
  */