reactor-core/src/main/java/reactor/core/publisher/Flux.java
public final Mono<Void> then() {
		@SuppressWarnings("unchecked")
		Mono<Void> then = (Mono<Void>) new MonoIgnoreElements<>(this);
		return Mono.onAssembly(then);
	}
public final Mono<Void> then() {
		@SuppressWarnings("unchecked")
		Mono<Void> then = (Mono<Void>) new MonoIgnoreElements<>(this);
		return Mono.onAssembly(then);
	}
Return a {@code Mono<Void>} that completes when this {@link Flux} completes.
This will actively ignore the sequence and only replay completion or error signals.
<p>
<img class="marble" src="doc-files/marbles/thenForFlux.svg" alt="">
<p>

@reactor.discard This operator discards elements from the source.

@return a new {@link Mono} representing the termination of this {@link Flux}