public boolean isDowngradeAllowed() {
    if (m_direction == Direction.DOWNGRADE) {
      return false;
    }

    return m_upgradePack.isDowngradeAllowed();
  }
Gets whether a downgrade is allowed for this upgrade. If the direction is
{@link Direction#DOWNGRADE}, then this method always returns false.
Otherwise it will consule {@link UpgradePack#isDowngradeAllowed()}.

@return {@code true} of a downgrade is allowed for this upgrade,
        {@code false} otherwise.
ambari-server/src/main/java/org/apache/ambari/server/stack/upgrade/orchestrate/UpgradeContext.java