@Override
  public String toString() {
    StringBuilder desc = new StringBuilder();
    desc.append("VersionedObjectList(regionVersioned=").append(regionIsVersioned)
        .append("; hasKeys=").append(hasKeys).append("; keys=")
        .append(keys == null ? "null" : String.valueOf(keys.size())).append("; objects=")
        .append(objects.size()).append("; isobject=")
        .append(objectTypeArray == null ? "null" : objectTypeArray.length).append("; ccEnabled=")
        .append(regionIsVersioned).append("; versionTags=")
        .append(versionTags.size()).append(")\n");
    Iterator entries = iterator();
    while (entries.hasNext()) {
      desc.append(entries.next()).append("\n");
    }
    return desc.toString();
  }
sets the keys for this partlist
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/VersionedObjectList.java