Method apply

src/jmh/java/io/reactivex/rxjava3/core/XMapYPerf.java:105–108

(Integer v)

        flowFlatMapFlowable1 = fsource.flatMap(new Function<Integer, Publisher<Integer>>() {
            @Override
            public Publisher<Integer> apply(Integer v) {
                return Flowable.just(v);
            }
        });

        flowFlatMapFlowable0 = fsource.flatMap(new Function<Integer, Publisher<Integer>>() {