static L<Map> zipFileToJSONFingerprint_dateOnly(File zip) {
  temp zipFile = zipFile(zip);
  ret zipFileToJSONFingerprint_dateOnly(zipFile);
}

static L<Map> zipFileToJSONFingerprint_dateOnly(ZipFile zip) {
  ret map(listZipEntries(zip), e ->
    litorderedmap(name := e.getName(),
      date := e.getTime()/1000,
    ));
}