}
protected SourceValidity[] getCacheValidities() {
if (this.cache instanceof EventAware) {
// use event caching strategy, the associated event is the source uri
return new SourceValidity[] { new EventValidity(new NamedEvent(this.source.getURI())) };
} else {
// we need to store both the cache expiration and the original source validity
// the former is to determine whether to recheck the latter (see checkValidity)
return new SourceValidity[] { new ExpiresValidity(getExpiration()), source.getValidity() };
}