code: public List<IAtomContainer> getTautomers(IAtomContainer mol) throws CDKException, CloneNotSupportedException {
  
          String opt = "";
          if ((flags & KETO_ENOL) != 0)
              opt += " -KET";
          if ((flags & ONE_FIVE_SHIFT) != 0)
              opt += " -15T";
  
          InChIGenerator gen   = InChIGeneratorFactory.getInstance().getInChIGenerator(mol, opt);
          String         inchi = gen.getInchi();
          String         aux   = gen.getAuxInfo();
  
          long[] amap = new long[mol.getAtomCount()];
          InChINumbersTools.parseAuxInfo(aux, amap);
  
          if (inchi == null)
              throw new CDKException(InChIGenerator.class
                      + " failed to create an InChI for the provided molecule, InChI -> null.");
          return getTautomers(mol, inchi, amap);
      }
docs: Public method to get tautomers for an input molecule, based on the InChI which will be calculated by JNI-InChI.
  @param mol molecule for which to generate tautomers
  @return a list of tautomers, if any
  @throws CDKException
  @throws CloneNotSupportedException