code: public static int compare (Comparable<?> c1, Comparable<?> c2)
      {
          @SuppressWarnings("unchecked") Comparable<Object> cc1 = (Comparable<Object>)c1;
          @SuppressWarnings("unchecked") Comparable<Object> cc2 = (Comparable<Object>)c2;
          return cc1.compareTo(cc2);
      }
docs: Compares the first comparable to the second. This is useful to avoid type safety warnings
  when dealing with the keys of {@link DSet.Entry} values.