code: public List<CDKRMap> bitSetToRMap(BitSet set) {
          List<CDKRMap> rMapList = new ArrayList<CDKRMap>();
  
          for (int x = set.nextSetBit(0); x >= 0; x = set.nextSetBit(x + 1)) {
              CDKRNode xNode = getGraph().get(x);
              rMapList.add(xNode.getRMap());
          }
          return rMapList;
      }
docs: Converts a CDKRGraph bitset (set of CDKRNode)
  to a list of CDKRMap that represents the
  mapping between to substructures in G1 and G2
  (the projection of the CDKRGraph bitset on G1
  and G2).
  
  @param  set  the BitSet
  @return      the CDKRMap list