@Override
  public void fromData(DataInput in,
      DeserializationContext context) throws IOException, ClassNotFoundException {
    super.fromData(in, context);
    int numKeys = in.readInt();
    keys = new HashSet<>(numKeys);
    for (int i = 0; i < numKeys; i++) {
      keys.add(DataSerializer.readObject(in));
    }
    eventID = DataSerializer.readObject(in);
  }
Empty constructor to satisfy {@link DataSerializer} requirements
geode-core/src/main/java/org/apache/geode/internal/cache/partitioned/PRTombstoneMessage.java