tdcommon/src/main/java/thredds/server/catalog/tracker/CatalogWatcher.java
public void register(Path dir) throws IOException {
    if (!enable) return;

    WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
    if (trace) {
      Path prev = keys.get(key);
      if (prev == null) {
        System.out.format("CatalogWatcher register: %s%n", dir);
      } else {
        if (!dir.equals(prev)) {
          System.out.format("update: %s -> %s%n", prev, dir);
        }
      }
    }
    keys.put(key, dir);
  }
public void register(Path dir) throws IOException {
    if (!enable) return;

    WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
    if (trace) {
      Path prev = keys.get(key);
      if (prev == null) {
        System.out.format("CatalogWatcher register: %s%n", dir);
      } else {
        if (!dir.equals(prev)) {
          System.out.format("update: %s -> %s%n", prev, dir);
        }
      }
    }
    keys.put(key, dir);
  }
Register the given directory with the WatchService