public Set<Path> poll() {
    Set<Path> result = new TreeSet<>();
    for (var path : List.copyOf(modificationTimes.keySet())) {
      if (watch(path)) {
        result.add(path);
      }
    }
    return result;
  }
Returns the (normalized) paths modified since the last call to poll.
planetiler-core/src/main/java/com/onthegomap/planetiler/util/FileWatcher.java