private boolean hasSeenEvent(EntryEventImpl event) {
    assert event != null;
    if (event.getEventId() == null) {
      return false;
    }
    return seenEvents.contains(event.getEventId());
  }
keeps track of TransactionDataRebalancedException during txPutEntry
geode-core/src/main/java/org/apache/geode/internal/cache/TXState.java