Resolved: execute 2 Mono sequentialy not supporte blocking

Mono<Void> messageEvent(MessageEvent messageEvent);
Mono<Victim> getPersonById(String personId);

    spi.messageEvent(message).doOnSuccess(it -> {
        spi.getPersonById(evt.getVictimId()).doOnSuccess(victim -> {
            repository.save(victim);
        }).block();
    }).block();

/**
 * Let this {@link Mono} complete then play another Mono.
 * <p>
 * In other words ignore element from this {@link Mono} and transform its completion signal into the
 * emission and completion signal of a provided {@code Mono<V>}. Error signal is
 * replayed in the resulting {@code Mono<V>}.
 *
 * <p>
 * <img class="marble" src="doc-files/marbles/thenWithMonoForMono.svg" alt="">
 *
 * <p><strong>Discard Support:</strong> This operator discards the element from the source.
 *
 * @param other a {@link Mono} to emit from after termination
 * @param <V> the element type of the supplied Mono
 *
 * @return a new {@link Mono} that emits from the supplied {@link Mono}
 */
public final <V> Mono<V> then(Mono<V> other) {

 return spi.messageEvent(message)
     .then(spi.getPersonById(evt.getVictimId()))
     .map(repository::save);