@Override public <U extends Comparable<? super U>>CompletableFuture<Optional<T>> maxBy(final Function<? super T,? extends U> function){
  return CompletableFuture.supplyAsync(null);
}

@ Override public < U extends Comparable < ? super U > > CompletableFuture < Optional < T > > maxBy ( final Function < ? super T , ? extends U > function ) { return CompletableFuture . supplyAsync ( null ) ; }
asynchronously capture the maximum value in this stream using the provided function
