Handling Original Exception in Spring WebClient Retry Strategy

Question

Let us say I have two GET APIs in a Spring Boot application:

@RestController
@RequestMapping("/api")
public class Controller {

    @GetMapping("/greet")
    public String greet() {
        System.out.println("greet called");
        if (Math.random() > 0.2) {
            throw new RuntimeException("Custom error");
        }
        return "Hello, this is your Spring Boot endpoint!";
    }

    @GetMapping("/testing")
    public String testing() {
        return WebClient.builder()
                .baseUrl("http://localhost:8082").build().get().uri("/api/greet").retrieve()
                .bodyToMono(String.class)
                .retryWhen(Retry.backoff(1, Duration.ofSeconds(10))).block();
    }
}

When I call the "greet" API (http://localhost:8082/api/greet), it correctly throws a RuntimeException with the message "Custom error" which is expected.

However, when I call the "testing" API (http://localhost:8082/api/testing), it throws a RetryExhaustedException.

I understand that the RetryExhaustedException is thrown when retries are exhausted. but I want the original API exception (RuntimeException("Custom error")) to be returned when calling the "testing" API.

How can I modify my code to achieve this?

I have tried to use onRetryExhaustedThrow and updated the Webclient code

    @GetMapping("/testing")
    public String testing() {
        return WebClient.builder()
                .baseUrl("http://localhost:8082").build().get().uri("/api/greet").retrieve()
                .bodyToMono(String.class)
                .retryWhen(Retry.backoff(1, Duration.ofSeconds(10))
                        .onRetryExhaustedThrow((retryBackoffSpec, retrySignal) -> retrySignal.failure()))
                .block();
    }

and then I call test API http://localhost:8082/api/testing but it not throws a RuntimeException with the message "Custom error"