code: public String formatDuration(Calendar then)
     {
        if (then == null)
           return formatDuration(now());
  
        Duration duration = approximateDuration(then.getTime());
        return formatDuration(duration);
     }
docs: Format the given {@link Calendar} and return a non-relative (not decorated with past or future tense)
  {@link String} for the approximate duration of its difference between the reference {@link Date}. If the given
  {@link Calendar} is <code>null</code>, the current value of {@link System#currentTimeMillis()} will be used
  instead.
  <p>
  
  @param then the date to be formatted
  @return A formatted string of the given {@link Date}