public boolean setRegionSynchronizedWithIfNotScheduled(VersionSource lostMemberVersionID) {
    RegionVersionHolder regionVersionHolder =
        getVersionVector().getHolderForMember(lostMemberVersionID);
    if (regionVersionHolder != null) {
      return regionVersionHolder.setRegionSynchronizeScheduledOrDoneIfNot();
    }
    return false;
  }
This method checks region version holder to see if regionSynchronizeScheduledOrDone is
set to true for the lost member. If it is not, the regionSynchronizeScheduledOrDone variable
is set to true and returns true. If it is already set to true, do nothing and returns false.
geode-core/src/main/java/org/apache/geode/internal/cache/DistributedRegion.java