public Set<AlertDefinitionEntity> getAlertDefinitions() {
    if (null == alertDefinitions) {
      alertDefinitions = new HashSet<>();
    }

    return Collections.unmodifiableSet(alertDefinitions);
  }
Gets all of the alert definitions that are a part of this grouping.

@return the alert definitions or an empty set if none (never {@code null).
ambari-server/src/main/java/org/apache/ambari/server/orm/entities/AlertGroupEntity.java