code: public int getValue(int index) {
          switch (index) {
              case YEAR:
                  return getChronology().year().get(getLocalMillis());
              case MONTH_OF_YEAR:
                  return getChronology().monthOfYear().get(getLocalMillis());
              case DAY_OF_MONTH:
                  return getChronology().dayOfMonth().get(getLocalMillis());
              case MILLIS_OF_DAY:
                  return getChronology().millisOfDay().get(getLocalMillis());
              default:
                  throw new IndexOutOfBoundsException("Invalid index: " + index);
          }
      }
docs: Gets the value of the field at the specified index.
  <p>
  This method is required to support the <code>ReadablePartial</code>
  interface. The supported fields are Year, MonthOfDay, DayOfMonth and MillisOfDay.
  
  @param index  the index, zero to two
  @return the value
  @throws IndexOutOfBoundsException if the index is invalid