code: public IAtom[] findTerminalAtoms(IAtomContainer container) {
          IAtom[] atoms = findTerminalAtoms(container, getFocus());
          List<IAtom> carriers = getCarriers();
          if (container.getBond(atoms[0], carriers.get(2)) != null ||
              container.getBond(atoms[0], carriers.get(3)) != null) {
              IAtom tmp = atoms[0];
              atoms[0] = atoms[1];
              atoms[1] = tmp;
          }
          return atoms;
      }
docs: Helper method to locate two terminal atoms in a container for this
  extended tetrahedral element. The atoms are ordered such that the first
  index is attached to the first two peripheral atoms and the second index
  is attached to the second two peripheral atoms.
  
  @param container structure representation
  @return the terminal atoms (ordered)