code: public String format(Calendar then)
     {
        if (then == null)
           return format(now());
        return format(then.getTime());
     }
docs: Format the given {@link Calendar} object. If the given {@link Calendar} is <code>null</code>, the current value of
  {@link System#currentTimeMillis()} will be used instead.
  
  @param then the {@link Calendar} whose date is to be formatted
  @return A formatted string representing {@code then}