code: public Chronology getChronology(Object object, DateTimeZone zone) {
          return getChronology(object, (Chronology) null).withZone(zone);
      }
docs: Gets the chronology, which is taken from the ReadablePartial.
  
  @param object  the ReadablePartial to convert, must not be null
  @param zone  the specified zone to use, null means default zone
  @return the chronology, never null