code: public static UUID attemptUUIDParse(BufferedString str) {
      Long lo = attemptUUIDParseLow(str);
      Long hi = attemptUUIDParseHigh(str);
      return (str.getOffset() == -1) ? null : buildUUID(lo, hi);
    }
docs: Attempts to parse the provided {@link BufferedString} as
  a UUID into hash value in two longs.
  
  Warning: as written, this method does modify the state
  of the passed in BufferedString.
  
  @param str
  @return A parsed UUID, or a null if parsing failed.