code: @Override
      public int getBondOrderSum() {
          int sum = 0;
          for (int i = 0; i < getBondCount(); i++) {
              IBond.Order order = getBond(i).getOrder();
              if (order != null) {
                  sum += order.numeric();
              }
          }
          return sum;
      }
docs: Returns the sum of all bond orders in the ring.
  
  @return the sum of all bond orders in the ring