code: @Override
      public void addBond(int atom1, int atom2, IBond.Order order, IBond.Stereo stereo) {
          IBond bond = getBuilder().newInstance(IBond.class, getAtom(atom1), getAtom(atom2), order, stereo);
  
          if (contains(bond)) {
              return;
          }
  
          if (bondCount >= bonds.length) {
              growBondArray();
          }
          addBond(bond);
          /*
           * no notifyChanged() here because addBond(bond) does it already
           */
      }
docs: Adds a bond to this container.
  
  @param  atom1   Id of the first atom of the Bond in [0,..]
  @param  atom2   Id of the second atom of the Bond in [0,..]
  @param  order   Bondorder
  @param  stereo  Stereochemical orientation