.html#updateDiskCacheKey-java.security.MessageDigest-"><code>Key.updateDiskCacheKey(java.security.MessageDigest)</code></a> should all change. If you're using a
 simple String key an easy way to do this is to append a version number to your key. Failing to
 do so will mean users may see images loaded from cache that had the old version of the
 Transformation applied. Changing the return values of those methods will ensure that the cache
 key has changed and therefore that any cached resources will be re-gen