class AbstractExpressionEvaluator implements ExpressionEvaluator {

    protected boolean isObjectEmpty(ObjectNode json) {
        Iterator<Map.Entry<String, JsonNode>> fields = json.fields();
        while (fields.hasNext()) {
            JsonNode element = fields.next().getValue();
            if (!isNodeEmpty(element)) {
                return false;
            }
        }
        return true;
    }

}