code: public Long optLong(String name, Long fallback) {
          return optLong(name, fallback, true);
      }
docs: Returns the value mapped by {@code name} if it exists and is a long or
  can be coerced to a long, or {@code fallback} otherwise. Note that Util represents
  numbers as doubles, so this is <a href="#lossy">lossy</a>; use strings to transfer
  numbers via Util.