// vars to "*"
static S upperCaseVarsToStars(S s, L<S> vars_out) {
  L<S> tok = javaTok(s);
  for (int i = 1; i < l(tok); i += 2)
    if (startsWithUpperCase(tok.get(i))) {
      vars_out.add(tok.get(i));
      tok.set(i, "*");
    }
  ret join(tok);
}