code: public static boolean stereosAreOpposite(IAtomContainer container, IAtom atom) {
          List<IAtom> atoms = container.getConnectedAtomsList(atom);
          TreeMap<Double, Integer> hm = new TreeMap<Double, Integer>();
          for (int i = 1; i < atoms.size(); i++) {
              hm.put(giveAngle(atom, atoms.get(0), atoms.get(i)), i);
          }
          Object[] ohere = hm.values().toArray();
          IBond.Stereo stereoOne = container.getBond(atom, atoms.get(0)).getStereo();
          IBond.Stereo stereoOpposite = container.getBond(atom, atoms.get((Integer) ohere[1])).getStereo();
          return stereoOpposite == stereoOne;
      }
docs: Says if of four atoms connected two one atom the up and down bonds are
  opposite or not, i. e.if it's tetrehedral or square planar. The method
  does not check if there are four atoms and if two or up and two are down
  
  @param  atom          The atom which is the center
  @param  container  The atomContainer the atom is in
  @return            true=are opposite, false=are not