public synchronized boolean setRegionSynchronizeScheduledOrDoneIfNot() {
    if (!isRegionSynchronizeScheduledOrDone()) {
      regionSynchronizeScheduledOrDone = true;
      return true;
    }
    return false;
  }
Check to see if regionSynchronizeScheduledOrDone is set to true. 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/versions/RegionVersionHolder.java