public void flush() {
   changes.flush();
 }
 public void stop(Key k, long expiration) {
   changes.stop(k, expiration);
 }
 public void monitor(Key k, long expiration) {
   changes.monitor(k, expiration);
 }
 public void replace(Key k, long oldExpiration, long expiration) {
   changes.replace(k, expiration, oldExpiration);
 }
 private void updateTimeMapWithIncomingChanges() {
   changes.visitIncoming(treemap);
 }