public <R>FutureW<R> flatMapCf(final Function<? super T,? extends CompletionStage<? extends R>> mapper){
  return FutureW.<R>of(future.<R>thenCompose(null));
}

public < R > FutureW < R > flatMapCf ( final Function < ? super T , ? extends CompletionStage < ? extends R > > mapper ) { return FutureW . < R > of ( future . < R > thenCompose ( null ) ) ; }
a flatmap operation that accepts a completeablefuture completionstage as the return type
