code: public static void addNormalizerToModel(File f, Normalizer<?> normalizer) {
          File tempFile = null;
          try {
              // copy existing model to temporary file
              tempFile = DL4JFileUtils.createTempFile("dl4jModelSerializerTemp", "bin");
              tempFile.deleteOnExit();
              Files.copy(f, tempFile);
              try (ZipFile zipFile = new ZipFile(tempFile);
                   ZipOutputStream writeFile =
                           new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(f)))) {
                  // roll over existing files within model, and copy them one by one
                  Enumeration<? extends ZipEntry> entries = zipFile.entries();
                  while (entries.hasMoreElements()) {
                      ZipEntry entry = entries.nextElement();
  
                      // we're NOT copying existing normalizer, if any
                      if (entry.getName().equalsIgnoreCase(NORMALIZER_BIN))
                          continue;
  
                      log.debug("Copying: {}", entry.getName());
  
                      InputStream is = zipFile.getInputStream(entry);
  
                      ZipEntry wEntry = new ZipEntry(entry.getName());
                      writeFile.putNextEntry(wEntry);
  
                      IOUtils.copy(is, writeFile);
                  }
                  // now, add our normalizer as additional entry
                  ZipEntry nEntry = new ZipEntry(NORMALIZER_BIN);
                  writeFile.putNextEntry(nEntry);
  
                  NormalizerSerializer.getDefault().write(normalizer, writeFile);
              }
          } catch (Exception ex) {
              throw new RuntimeException(ex);
          } finally {
              if (tempFile != null) {
                  tempFile.delete();
              }
          }
      }
docs: This method appends normalizer to a given persisted model.
  
  PLEASE NOTE: File should be model file saved earlier with ModelSerializer
  
  @param f
  @param normalizer