If the configured "hashKeyMask" value is changed for an existing cache store, the whole cache store becomes unusable.
Parts of the cache store configuration should be persisted in the file cache store and checked upon startup.
If the existing (persistent) configuration is different from what the user has set in the configuration XML (or programatically), two things are possible:
1. print a WARNING that the cache store uses the persistent configuration
2. like 1, but perform a re-hash of the file cache store, if a certain configuration option has been set