reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final Mono<T> doAfterTerminate(Runnable afterTerminate) {
		Objects.requireNonNull(afterTerminate, "afterTerminate");
		return doAfterSuccessOrError((s, e)  -> afterTerminate.run());
	}
public final Mono<T> doAfterTerminate(Runnable afterTerminate) {
		Objects.requireNonNull(afterTerminate, "afterTerminate");
		return doAfterSuccessOrError((s, e)  -> afterTerminate.run());
	}
Add behavior (side-effect) triggered after the {@link Mono} terminates, either by
completing downstream successfully or with an error.
<p>
<img class="marble" src="doc-files/marbles/doAfterTerminateForMono.svg" alt="">

@param afterTerminate the callback to call after {@link Subscriber#onComplete} or {@link Subscriber#onError}

@return an observed  {@link Flux}