public byte[] lastUpdate(byte[] in, int offset, int length) throws TransformerException
public byte[] lastUpdate() throws TransformerException
  public byte[] lastUpdate(byte[] in, int offset, int length)      throws TransformerException  {    byte[] result = update(in, offset, length);    byte[] rest = lastUpdate();    if (rest.length > 0)      {        byte[] newResult = new byte[result.length + rest.length];        System.arraycopy(result, 0, newResult, 0, result.length);        System.arraycopy(rest, 0, newResult, result.length, rest.length);        result = newResult;      }    return result;  }