void bringAllInstancesUp() {
    for (MockHelixAdmin helixAdmin : helixAdmins.values()) {
      for (String instance : helixAdmin.getDownInstances()) {
        helixAdmin.bringInstanceUp(instance);
      }
    }
    if (isAggregatedViewUsed) {
      localHelixAdmin.triggerLiveInstanceChangeNotification();
    } else {
      helixAdmins.values().forEach(MockHelixAdmin::triggerLiveInstanceChangeNotification);
    }
  }
Bring all instances in this cluster up.
ambry-clustermap/src/test/java/com/github/ambry/clustermap/MockHelixCluster.java