public static <T> Collector<T, ?, Optional<Long>> denseRank(T value, Comparator<? super T> comparator) {
        return denseRankBy(value, t -> t, comparator);
    }
Get a {@link Collector} that calculates the <code>DENSE_RANK()</code> function given a specific ordering.
jOOL-java-8/src/main/java/org/jooq/lambda/Agg.java