static LS fileNamesInZipWithExtension(ZipFile zip, S ext) {
  fS suffix = addPrefixIfNotEmpty2(".", ext);
  ret [S name : listZipFile(zip) | ewic(name, suffix)];
}


static LS fileNamesInZipWithExtension(File zip, S ext) {
  temp ZipFile zipFile = openZipFile(zip);
  ret fileNamesInZipWithExtension(zipFile, ext);
}