private void OnBookRenamed(KeyValuePair<string, string> fromPathAndToPath)
{
//Note, we don't pay attention to what the change was, we just purge the whole cache
TryToDeleteCachedImages();
_originalPathToProcessedVersionPath = new ConcurrentDictionary<string, string>();
_imageFilesToReturnUnprocessed = new ConcurrentDictionary<string, bool>();
}