protected EventID distributeTombstoneGC(Set<Object> keysRemoved) {
    getCachePerfStats().incTombstoneGCCount();
    EventID eventId = new EventID(getSystem());
    DistributedTombstoneOperation gc = DistributedTombstoneOperation.gc(this, eventId);
    gc.distribute();
    notifyClientsOfTombstoneGC(getVersionVector().getTombstoneGCVector(), keysRemoved, eventId,
        null);
    return eventId;
  }
Distribute Tombstone garbage-collection information to all peers with storage
geode-core/src/main/java/org/apache/geode/internal/cache/DistributedRegion.java