docs: public Selector getSelector(String selector) {
      Selector ans;
      try {
        ans = QueryExpr();
        if (!ans.mayBeBoolean())
          ans.setType(Selector.INVALID);
      } catch (ParseException e) {
        // No FFDC code needed
        Object obj = null;
        ans = new LiteralImpl(obj);
        ans.setType(Selector.INVALID);
      }
      return ans;
    }