code: public IsotopePattern getIsotopes(IMolecularFormula molFor) {
  
          if (builder == null) {
              try {
                  isoFactory = Isotopes.getInstance();
                  builder = molFor.getBuilder();
              } catch (Exception e) {
                  e.printStackTrace();
              }
          }
          String mf = MolecularFormulaManipulator.getString(molFor, true);
  
          IMolecularFormula molecularFormula = MolecularFormulaManipulator.getMajorIsotopeMolecularFormula(mf, builder);
  
          IsotopePattern abundance_Mass = null;
  
          for (IIsotope isos : molecularFormula.isotopes()) {
              String elementSymbol = isos.getSymbol();
              int atomCount = molecularFormula.getIsotopeCount(isos);
  
              // Generate possible isotope containers for the current atom's
              // these will then me 'multiplied' with the existing patten
              List<IsotopeContainer> additional = new ArrayList<>();
              for (IIsotope isotope : isoFactory.getIsotopes(elementSymbol)) {
                  double mass      = isotope.getExactMass();
                  double abundance = isotope.getNaturalAbundance();
                  if (abundance <= 0.000000001)
                      continue;
                  IsotopeContainer container = new IsotopeContainer(mass, abundance);
                  if (storeFormula)
                      container.setFormula(asFormula(isotope));
                  additional.add(container);
              }
  
              for (int i = 0; i < atomCount; i++)
                  abundance_Mass = calculateAbundanceAndMass(abundance_Mass, additional);
          }
  
          IsotopePattern isoP = IsotopePatternManipulator.sortAndNormalizedByIntensity(abundance_Mass);
          isoP = cleanAbundance(isoP, minIntensity);
          IsotopePattern isoPattern = IsotopePatternManipulator.sortByMass(isoP);
          return isoPattern;
  
      }
docs: Get all combinatorial chemical isotopes given a structure.
  
  @param molFor  The IMolecularFormula to start
  @return        A IsotopePattern object containing the different combinations