private void unlockVersionGeneration(final InternalDistributedMember locker) {
    synchronized (clearLockSync) {
      doUnlock = true;
      clearLockSync.notifyAll();
    }
  }
This schedules a thread that owns the version-generation write-lock for this vector. The method
unlockVersionGeneration notifies the thread to release the lock and terminate its run.

@param dm the distribution manager - used to obtain an executor to hold the thread
@param locker the member requesting the lock (currently not used)
geode-core/src/main/java/org/apache/geode/internal/cache/versions/RegionVersionVector.java