Provide a way to obtain Container Item from CalendarEvent

When overridin methods such as moveEvent, resizeEvent or clickEvent, one gets an instance of appropriate CalendarComponentEvent, which holds a reference to an instance of ContainerCalendarEvent, which is a private inner class (so one can't cast the event object to it). When using this provider combined with (for exapmle) JPAContainer, there is no way to obtain an instance of the real event (which can be an entity, managed by the container). This severely limits the possibilities of extending ContainerEventProvider.