sclass Zip2Zip_b {
  // must set
  File inZip;
  ZipOutputStream outZip;
  new Set<S> filesWritten;
  
  // optional
  IPred<S> predicate;
  
  *(File *inZip, ZipOutputStream *outZip, Set<S> *filesWritten) {}
  *(ZipOutputStream *outZip) {}
  
  run {
    ZipFile zipFile = new ZipFile(inZip);
    try {
      Enumeration entries = zipFile.entries();
      while (entries.hasMoreElements()) {
        ZipEntry entry = (ZipEntry) entries.nextElement();
        if (entry.isDirectory()) continue;
        S name = entry.getName();
        
        if (predicate != null && !predicate.get(name)) continue;
        if (!filesWritten.add(name)) continue;
        
        modifyZipEntry(entry);
        outZip.putNextEntry(entry);
        copyStreamAndCloseInput(zipFile.getInputStream(entry), outZip);
      }
    } finally {
      zipFile.close();
    }
  }
  
  swappable void modifyZipEntry(ZipEntry e) {}
}

Began life as a copy of #1033332