Invoked when Tapestry notices
that the implementation class has changed. The existing instance is notified, so that
it can cleanly shutdown now, before being re-instantiated. This is necessary when the
service implementation retains some form of external resources.
In addition, the implementation may request an immediate reload. Normally, reloading of the service is deferred
until a method of the proxy object is invoked (this causes the normal just-in-time instantiation of the
implementation). When this method returns true, the implementation is re-created immediately. This is most often
the case for services that are eagerly loaded in the first place.
true if the service should be reloaded immediately, false if reload should be deferred