reactor-core/src/main/java/reactor/core/publisher/Flux.java
public final <U> Flux<T> sample(Publisher<U> sampler) {
		return onAssembly(new FluxSample<>(this, sampler));
	}
public final <U> Flux<T> sample(Publisher<U> sampler) {
		return onAssembly(new FluxSample<>(this, sampler));
	}
Sample this {@link Flux} by emitting an item corresponding to that {@link Flux}
latest emitted value whenever a companion sampler {@link Publisher} signals a value.
<p>
Termination of either {@link Publisher} will result in termination for the {@link Subscriber}
as well.
Note that if some elements are emitted just before source completion and before a
last sampler can trigger, the last of these elements will be emitted along with the
onComplete signal.
<p>
Both {@link Publisher} will run in unbounded mode because the backpressure
would interfere with the sampling precision.

<p>
<img class="marble" src="doc-files/marbles/sampleWithSampler.svg" alt="">

@reactor.discard This operator discards elements that are not part of the sampling.

@param sampler the sampler companion {@link Publisher}

@param <U> the type of the sampler sequence

@return a {@link Flux} sampled to the last item observed each time the sampler {@link Publisher} signals