afterCreate event is fired even in case of update -How Events works in Gemfire?

Client Cache Configuration -

    <region name="test" refid="PROXY">
        <region-attributes>
            <cache-listener>
                <class-name>com.test.cache.SimpleCacheListener</class-name>
            </cache-listener>
        </region-attributes>
    </region>

For the above client side configuration , I have used a CacheListener which listens to events on this cache "test".

The issue that i am facing is even on update event , i.e putting a different value for same key in cache , an afterCreate Event is fired.

i.e.

   region.put("test key","test value")

and

    region.put("test key","test updated value")

both generate an afterCreateEvent in Listener.

Please help and let me know if i am missing something.