* @return the adjusted object, not null
   */
  @Override
  public DateTime doWithAdjustment(DateTime dateTime) {

    if (Chrono.from(dateTime).equals(ISOChrono.INSTANCE) == false) {
      throw new DateTimeException("Adjustment only supported on ISO date-time");
    }
    return dateTime.with(EPOCH_MONTH, getEpochMonth());
  }