public static <T, U extends Comparable<? super U>> Collector<T, ?, Optional<T>> maxBy(Function<? super T, ? extends U> function) {
        return maxBy(function, naturalOrder());
    }
Get a {@link Collector} that calculates the <code>MAX()</code> function.
jOOL-java-8/src/main/java/org/jooq/lambda/Agg.java