@Override
  public void toData(DataOutput out,
      SerializationContext context) throws IOException {
    toData(out, context, 0, regionIsVersioned ? versionTags.size() : size(), true, true);
  }
sets the keys for this partlist
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/VersionedObjectList.java