public void setRegionSynchronizeScheduled(VersionSource lostMemberVersionID) {
    RegionVersionHolder regionVersionHolder =
        getVersionVector().getHolderForMember(lostMemberVersionID);
    if (regionVersionHolder != null) {
      regionVersionHolder.setRegionSynchronizeScheduled();
    }
  }
This is invoked by syncForCrashedMember when scheduling region synchronization
triggered by member departed event. It sets the regionSynchronizeScheduledOrDone
flag in region version holder to true. This indicates that no additional region sync for
the lost member is needed, when it receives requests for region sync for the lost member.
geode-core/src/main/java/org/apache/geode/internal/cache/DistributedRegion.java