@Subscribe
  public void jpaInitialized(JpaInitializedEvent event) {
    LOGGER.info("JPA initialized event received: {}", event);
    jpaStarted.set(true);
    instance = loadInstance();
  }
Upon receiving this event, the JPA infrastructure has completed initialization and the relevant
data may be retrieved.

@param event the received {@link JpaInitializedEvent}
ambari-server/src/main/java/org/apache/ambari/server/configuration/AmbariServerConfigurationProvider.java