public void addAlertTarget(AlertTargetEntity alertTarget) {
    if (null == alertTargets) {
      alertTargets = new HashSet<>();
    }

    alertTargets.add(alertTarget);
    alertTarget.addAlertGroup(this);
  }
Adds the specified target to the targets that this group will dispatch to.

@param alertTarget
         the target to add (not {@code null}).
ambari-server/src/main/java/org/apache/ambari/server/orm/entities/AlertGroupEntity.java