code: public static byte[] concat(final byte[]... arrays) {
      int len = 0;
      for (final byte[] arr : arrays) {
        len += arr.length;
      }
  
      final byte[] result = new byte[len];
      int pos = 0;
      for (final byte[] arr : arrays) {
        System.arraycopy(arr, 0, result, pos, arr.length);
        pos += arr.length;
      }
      return result;
    }
docs: Concatenate byte arrays into one byte array sequentially.
  
  @param arrays arrays to be concatenated
  @return the result byte array contains concatenated source arrays
  @since 1.1