CacheMonoValue.java

private static class CacheMonoValue<VALUE> {

    private Mono<VALUE> mono;
    private Signal<VALUE> signal;

    CacheMonoValue(Mono<VALUE> mono) {
        this.mono = mono;
    }

    CacheMonoValue(Signal<VALUE> signal) {
        this.signal = signal;
    }

    Mono<VALUE> toMono() {
        if (mono != null) {
            return mono;
        }
        return Mono.justOrEmpty(signal).dematerialize();
    }

    Optional<VALUE> getValue() {
        if (signal == null) {
            return Optional.empty();
        }
        return Optional.ofNullable(signal.get());
    }
}