code: public Guid append(byte[]... byteArrays) throws IOException {
      if (byteArrays == null || byteArrays.length == 0) {
        return this;
      }
      return fromByteArrays(ArrayUtils.add(byteArrays, this.sha));
    }
docs: Creates a new {@link Guid} which is a unique, replicable representation of the pair (this, byteArrays).
  @param byteArrays an array of byte arrays.
  @return a new {@link Guid}.
  @throws IOException