reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final <V> Flux<V> thenMany(Publisher<V> other) {
		@SuppressWarnings("unchecked")
		Flux<V> concat = (Flux<V>)Flux.concat(ignoreElement(), other);
		return Flux.onAssembly(concat);
	}
public final <V> Flux<V> thenMany(Publisher<V> other) {
		@SuppressWarnings("unchecked")
		Flux<V> concat = (Flux<V>)Flux.concat(ignoreElement(), other);
		return Flux.onAssembly(concat);
	}
Let this {@link Mono} complete then play another {@link Publisher}.
<p>
In other words ignore element from this mono and transform the completion signal into a
{@code Flux<V>} that will emit elements from the provided {@link Publisher}.

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

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

@param other a {@link Publisher} to emit from after termination
@param <V> the element type of the supplied Publisher

@return a new {@link Flux} that emits from the supplied {@link Publisher} after
this Mono completes.