@Nullable
  private static RepositoryModels read(final IonReader reader, final ReadContext context) {
    if (reader.next() == null) return null;
    reader.stepIn();

    RepositoryModels model =
      context.objectMap.computeIfAbsent(readInt(reader, OBJECT_ID_FIELD), new SimpleObjectFactory<DefaultRepositoriesModel>() {

        @Override
        public DefaultRepositoriesModel create() {
          List<MavenRepositoryModel> repositories = readRepositories(reader, context);
          return new DefaultRepositoriesModel(repositories);
        }
      });
    reader.stepOut();
    return model;
  }
@Nullable
  private static RepositoryModels read(final IonReader reader, final ReadContext context)