public Set getKeys() {
    Set keys = new HashSet(getSize());
    for (final PutAllEntryData putAllPRDatum : putAllPRData) {
      if (putAllPRDatum != null) {
        keys.add(putAllPRDatum.getKey());
      }
    }
    return keys;
  }
Empty constructor to satisfy {@link DataSerializer}requirements
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/PutAllPRMessage.java