WatchServiceDirectoryScanner does not handle OVERFLOW event

The WatchServiceDirectoryScanner misses files when WatchService generates OVERFLOW events instead of ENTRY_CREATE. This can happen when a lot of files are getting written into a folder that is being watched and the event generator cannot keep up with the rate of event generation. When this happens, the entire folder needs to be re-scanned again and the watch service restored after all missed files are accounted for.