code: public static long[] symmetry(IAtomContainer container, int[][] g) {
          return new Canon(g, basicInvariants(container, g), terminalHydrogens(container, g), true).symmetry;
      }
docs: Compute the symmetry classes for the provided structure. There are known
  examples where symmetry is incorrectly found. The {@link
  EquivalentClassPartitioner} gives more accurate symmetry perception but
  this method is very quick and in practise successfully portions the
  majority of chemical structures.
  
  @param container structure
  @param g         adjacency list graph representation
  @return symmetry classes
  @see EquivalentClassPartitioner