class ImageMetaData {

    public void add(Map<String, String> labels2) {
        if (this.labels == null) {
            this.labels = new ArrayList<>();
            this.labels.add(labels2);
        } else {
            this.labels.get(0).putAll(labels2);
        }        
    }

    public  ImageMetaData();
    public  ImageMetaData(List<Map<String, String>> labels);

}