code: public static void markAromaticRings(IRingSet ringset) {
          for (IAtomContainer atomContainer : ringset.atomContainers()) {
              RingManipulator.markAromaticRings((IRing) atomContainer);
          }
      }
docs: Iterates over the rings in the ring set, and marks the ring
  aromatic if all atoms and all bonds are aromatic.
  
  This method assumes that aromaticity perception has been done before hand.
  
  @param ringset The collection of rings