code: @Override
      public Order getMinimumBondOrder(IAtom atom) {
          IBond.Order min = IBond.Order.QUADRUPLE;
          for (int i = 0; i < bondCount; i++) {
              if (bonds[i].contains(atom) && bonds[i].getOrder().ordinal() < min.ordinal()) {
                  min = bonds[i].getOrder();
              }
          }
          return min;
      }
docs: Returns the minimum bond order that this atom currently has in the context
  of this AtomContainer.
  
  @param  atom  The atom
  @return       The minimum bond order that this atom currently has