code: public static String generateMDL(final HELM2Notation helm2notation) throws BuilderMoleculeException, CTKException, NotationException, ChemistryException {
      LOG.debug("Generate smiles representation for the whole HELM molecule");
      String smiles = SMILES.getSMILESForAll(helm2notation);
      LOG.debug("Convert smiles to mol");
      return Chemistry.getInstance().getManipulator().convert(smiles, AbstractChemistryManipulator.StType.SMILES);
    }
docs: method to generate MDL for a HELM molecule
  
  @param helm2notation input HELM2Notation
  @return MDL
  @throws BuilderMoleculeException if the helm molecule can not be built
  @throws CTKException general ChemToolKit exception passed to HELMToolKit
  @throws NotationException if notation is not valid
  @throws ChemistryException if the Chemistry Engine can not be initialized