This Listener is invoked when a nested Region is being
processed by it's containee. This allows lifecycle implementations to
be notified of events when a regionController is being refreshed or validated
so that they can take over calling of nested regionController's refresh of validate
operations. ADF bindingContainer implementation will make sure that the
RegionController registered with the bindingContainer is invoked at the
end of all RegionListeners registered with it for both refresh and
Notified when a contained regionController's validate() method should be called.
Return true if regionController's validate logic needs to proceed with invoking
validate() on the regionController binding.