code: public void writeNestedLibrary(String destination, Library library)
              throws IOException {
          File file = library.getFile();
          JarEntry entry = new JarEntry(destination + library.getName());
          entry.setTime(getNestedLibraryTime(file));
          if (library.isUnpackRequired()) {
              entry.setComment("UNPACK:" + FileUtils.sha1Hash(file));
          }
          new CrcAndSize(file).setupStoredEntry(entry);
          writeEntry(entry, new InputStreamEntryWriter(new FileInputStream(file), true));
      }
docs: Write a nested library.
  
  @param destination the destination of the library
  @param library     the library
  @throws IOException if the write fails