enxCPQ.CPQ_API02_OrdMgmt apiOrd = enxCPQ.CPQ_Factory.getAPI02OrdMgmtImpl();
enxCPQ.T_Order order = apiOrd.getOrder('ORD00YIAPOJJAWO');
// As of 2.8 eCPQ, it's mandatory workaround to avoid serialization error via enxCPQ.CPQ_Utils
for(enxCPQ.T_OrderItem item : order.orderItems) {
    item.fields = null;
}
UTIL.log(enxCPQ.CPQ_Utils.serialize(order));