private boolean hasToTrackKeysForClients(DistributedRegion r) {
      return r.isUsedForPartitionedRegionBucket()
          && ((r.getFilterProfile() != null && r.getFilterProfile().hasInterest())
              || r.getPartitionedRegion().getRegionAdvisor().hasPRServerWithInterest());
    }
Returns true if keys needs to be tracked for clients registering interests on PR.
geode-core/src/main/java/org/apache/geode/internal/cache/TombstoneService.java