code: private IAtom[] getBridgeAtoms(IAtomContainer sharedAtoms) {
          IAtom[] bridgeAtoms = new IAtom[2];
          IAtom atom;
          int counter = 0;
          for (int f = 0; f < sharedAtoms.getAtomCount(); f++) {
              atom = sharedAtoms.getAtom(f);
              if (sharedAtoms.getConnectedAtomsList(atom).size() == 1) {
                  bridgeAtoms[counter] = atom;
                  counter++;
              }
          }
          return bridgeAtoms;
      }
docs: Returns the bridge atoms, that is the outermost atoms in
  the chain of more than two atoms which are shared by two rings
  
  @param   sharedAtoms  The atoms (n > 2) which are shared by two rings
  @return  The bridge atoms, i.e. the outermost atoms in the chain of more than two atoms which are shared by two rings