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.