code: static boolean accept(IAtom atom, List<IBond> bonds) {
  
          int dbCount = 0;
  
          // not SP2
          if (!IAtomType.Hybridization.SP2.equals(atom.getHybridization())) return false;
  
          // only have one neighbour (which is the other atom) -> this is no configurable
          if (bonds.size() == 1) return false;
  
          for (IBond bond : bonds) {
  
              // increment the number of double bonds
              if (DOUBLE.equals(bond.getOrder())) dbCount++;
  
              // up/down bonds sometimes used to indicate E/Z
              IBond.Stereo stereo = bond.getStereo();
              if (IBond.Stereo.UP_OR_DOWN.equals(stereo) || IBond.Stereo.UP_OR_DOWN_INVERTED.equals(stereo))
                  return false;
  
          }
  
          // not cumulated
          return dbCount == 1;
      }
docs: Test whether we accept atom and it's connected bonds for inclusion in a
  double bond configuration. This method checks for query bonds (up/down)
  as well as double bond counts. If there is more then one double bond in
  the connect bonds then it cannot have Z/E configuration.
  
  @param atom  a double bonded atom
  @param bonds all bonds connected to the atom
  @return whether the atom is accepted for configuration