code: public IRingSet findSSSR() {
          if (atomContainer == null) {
              return null;
          }
          IRingSet ringSet = toRingSet(atomContainer, cycleBasis().cycles());
          //		atomContainer.setProperty(CDKConstants.SMALLEST_RINGS, ringSet);
          return ringSet;
  
      }
docs: Finds a Smallest Set of Smallest Rings.
  The returned set is not uniquely defined.
  
  @return      a RingSet containing the SSSR