issue with afterTaskActivatedEvent method of TaskLifeCycleEventListener

I am writing the custom TaskListener by implementing TaskLifeCycleEventListener interface and overriding the afterTaskActivatedEvent method. afterTaskActivatedEvent method is never getting called during the runtime.

issue was discussed with Redhat Technical support.

public class Listener implements TaskLifeCycleEventListener{

@Override
public void afterTaskActivatedEvent(TaskEvent event)

}