static void tok_addFieldOrder(L<S> tok, int i) {
  int idx = findCodeTokens(tok, i, false, "{");
  if (idx < 0) ret;
  int j = findEndOfBracketPart(tok, idx);
  L<S> vars = allVarNames(subList(tok, idx+1, j-1));
  //print("addFieldOrder " + struct(vars));
  if (nempty(vars) && !vars.contains("_fieldOrder")
    && !isSortedList(vars)) {
    //print("Adding field order");
    tok.set(idx+2, "static final String _fieldOrder = " + quote(join(" ", vars)) + ";\n  " + tok.get(idx+2));
    // reTok has to be done by caller
  }
}