code: public static int getSingleBondEquivalentSum(IAtomContainer container) {
          int sum = 0;
          for (IBond bond : container.bonds()) {
              IBond.Order order = bond.getOrder();
              if (order != null) {
                  sum += order.numeric();
              }
          }
          return sum;
      }
docs: Returns the sum of bond orders, where a single bond counts as one
  <i>single bond equivalent</i>, a double as two, etc.