reactor-core/src/main/java/reactor/core/publisher/Mono.java
public final Mono<T> repeatWhenEmpty(int maxRepeat, Function<Flux<Long>, ? extends Publisher<?>> repeatFactory) {
		return Mono.defer(() -> {
			Flux<Long> iterations;

			if(maxRepeat == Integer.MAX_VALUE) {
				iterations = Flux.fromStream(LongStream.range(0, Long.MAX_VALUE).boxed());
			}
			else {
				iterations = Flux
					.range(0, maxRepeat)
					.map(Integer::longValue)
					.concatWith(Flux.error(new IllegalStateException("Exceeded maximum number of repeats"), true));
			}

			return this.repeatWhen(o -> repeatFactory.apply(o
						.zipWith(iterations, 1, (c, i) -> i)))
			           .next();
		});
	}
public final Mono<T> repeatWhenEmpty(int maxRepeat, Function<Flux<Long>, ? extends Publisher<?>> repeatFactory) {
		return Mono.defer(() -> {
			Flux<Long> iterations;

			if(maxRepeat == Integer.MAX_VALUE) {
				iterations = Flux.fromStream(LongStream.range(0, Long.MAX_VALUE).boxed());
			}
			else {
				iterations = Flux
					.range(0, maxRepeat)
					.map(Integer::longValue)
					.concatWith(Flux.error(new IllegalStateException("Exceeded maximum number of repeats"), true));
			}

			return this.repeatWhen(o -> repeatFactory.apply(o
						.zipWith(iterations, 1, (c, i) -> i)))
			           .next();
		});
	}
Repeatedly subscribe to this {@link Mono} as long as the current subscription to this
{@link Mono} completes empty and the companion {@link Publisher} produces an onNext signal.
<p>
Any terminal signal will terminate the resulting {@link Mono} with the same signal immediately.
<p>
Emits an {@link IllegalStateException} if {@code maxRepeat} is exceeded (provided
it is different from {@code Integer.MAX_VALUE}).

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

@param maxRepeat the maximum number of repeats (infinite if {@code Integer.MAX_VALUE})
@param repeatFactory the {@link Function} that returns the associated {@link Publisher}
companion, given a {@link Flux} that signals each onComplete as a 0-based incrementing {@link Long}.

@return a {@link Mono} that resubscribes to this {@link Mono} if the previous subscription was empty,
as long as the companion {@link Publisher} produces an onNext signal and the maximum number of repeats isn't exceeded.