protected Set getRecipients() {
    DistributionAdvisee parent = newRegion.getParentAdvisee();
    Set recps = null;
    if (parent == null) { // root region, all recipients
      InternalDistributedSystem system = newRegion.getSystem();
      recps = system.getDistributionManager().getOtherDistributionManagerIds();
    } else {
      // get recipients that have the parent region defined as distributed.
      recps = getAdvice();
    }
    return recps;
  }
this method tells other members that the region is being created
geode-core/src/main/java/org/apache/geode/internal/cache/CreateRegionProcessor.java