@Override
  void basicUpdateEntryVersion(EntryEventImpl event) throws EntryNotFoundException {
    InternalRegion internalRegion = event.getRegion();
    AbstractRegionMap regionMap = (AbstractRegionMap) internalRegion.getRegionMap();
    regionMap.lockForCacheModification(internalRegion, event);
    final boolean locked = internalRegion.lockWhenRegionIsInitializing();
    try {
      try {
        if (!hasSeenEvent(event)) {
          super.basicUpdateEntryVersion(event);
        }
      } finally {
        if (!getConcurrencyChecksEnabled() || event.hasValidVersionTag()) {
          distributeUpdateEntryVersion(event);
        }
      }
    } finally {
      if (locked) {
        internalRegion.unlockWhenRegionIsInitializing();
      }
      regionMap.releaseCacheModificationLock(internalRegion, event);
    }
  }
Return true if invalidation occurred; false if it did not, for example if it was already
invalidated
geode-core/src/main/java/org/apache/geode/internal/cache/DistributedRegion.java