code: private boolean isTheSame(IIsotope isotopeOne, IIsotope isotopeTwo) {
          // XXX: floating point comparision!
          if (!Objects.equals(isotopeOne.getSymbol(), isotopeTwo.getSymbol())) return false;
          if (!Objects.equals(isotopeOne.getNaturalAbundance(), isotopeTwo.getNaturalAbundance())) return false;
          if (!Objects.equals(isotopeOne.getExactMass(), isotopeTwo.getExactMass())) return false;
  
          return true;
      }
docs: Compare to IIsotope. The method doesn't compare instance but if they
  have the same symbol, natural abundance and exact mass.
  
  @param isotopeOne   The first Isotope to compare
  @param isotopeTwo   The second Isotope to compare
  @return             True, if both isotope are the same