Nicht-blockierende WebClient-Anfragen mit Timeout und Fallback

@Service
public class CurrencyConversionService {
 
    private final WebClient webClient;
 
    public CurrencyConversionService(WebClient.Builder builder) {
        this.webClient = builder.baseUrl("https://api.fxrates.example.com").build();
    }
 
    public Mono<BigDecimal> fetchExchangeRate(String currency) {
        return webClient.get()
            .uri("/rates/{currency}", currency)
            .retrieve()
            .bodyToMono(BigDecimal.class)
            .timeout(Duration.ofMillis(1500))
            .onErrorReturn(TimeoutException.class, BigDecimal.ONE);
    }
}