* <p>This version of getKey is only called by ICUServiceFactories within the scope
* of a previous getKey call, to determine what previously-registered factories would
* have returned. For details, see getKey(ICUServiceKey&, UErrorCode&). Subclasses
* <p>This version of getKey is only called by ICUServiceFactories within the scope
* of a previous getKey call, to determine what previously-registered factories would
* have returned. For details, see getKey(ICUServiceKey&, UErrorCode&). Subclasses