@Override
  protected void basicClear(RegionEventImpl regionEvent) {
    Lock dlock = getRegionDistributedLockIfGlobal();
    try {
      super.basicClear(regionEvent);
    } finally {
      if (dlock != null) {
        dlock.unlock();
      }
    }
  }
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