code: @SuppressWarnings("deprecation")
    public static void getAsciiBytes(String element, int charStart, int charLen, byte[] bytes, int byteOffset) {
      element.getBytes(charStart, charLen, bytes, byteOffset);
    }
docs: This method is faster for ASCII data, but unsafe otherwise
  it is used by our macros AFTER checking that the string is ASCII
  following a pattern seen in Kryo, which benchmarking showed helped.
  Scala cannot supress warnings like this so we do it here