gistfile1.txt

@SpringBootApplication
@RestController
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}


	@GetMapping("/something")
	Mono<Void> something() {
		return Mono.error(new Throwable("mensaje"));
	}
}

gistfile2.txt

@ControllerAdvice
public class ExHandler {

    @ExceptionHandler(Throwable.class)
    @ResponseBody
    Complex handleAll(Throwable ex) {
        return new Complex();
    }

    @Data
    public static class Complex {
        String something;
    }
}

gistfile3.txt

dependencies {
	compile('org.springframework.boot:spring-boot-starter-webflux')
	compileOnly('org.projectlombok:lombok')
	testCompile('org.springframework.boot:spring-boot-starter-test')
	testCompile('io.projectreactor:reactor-test')
}