invalidContentConsumers, changesSince );
dirWalker.addDirectoryWalkListener( scannerInstance );
// Execute scan.
dirWalker.scan();
RepositoryScanStatistics stats = scannerInstance.getStatistics();
stats.setKnownConsumers( gatherIds( knownContentConsumers ) );
stats.setInvalidConsumers( gatherIds( invalidContentConsumers ) );