I'm trying to get a StreamingResponseBody from a @RestController on a long running job. It times out after 30 seconds, no matter what configuration I try.

This is in Spring Boot 2.0.3.
I've used the below test which shows the same behavior to try and get the configuration correct.

```
@RestController
public class TestController {

    @RequestMapping("/streamtest")
    public StreamingResponseBody handleRequest () {
        return new StreamingResponseBody() {
            @Override
            public void writeTo (OutputStream out) throws IOException {
                for (int i = 0; i < 100000; i++) {
                    out.write((Integer.toString(i) + " - ").getBytes());
                    out.flush();
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
       };
   }
}

```

I've tried the async.request-timeout setting defined here;
[Async timeout downloading a large file using StreamingResponseBody on Spring Boot](https://stackoverflow.com/questions/42877498/async-timeout-downloading-a-large-file-using-streamingresponsebody-on-spring-boo#comment92771233_43496244)

I've tried overriding WebMvcConfig to set the timeout. This method is never called.

```
@EnableWebMvc
@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
        configurer.setDefaultTimeout(3600000);
        WebMvcConfigurer.super.configureAsyncSupport(configurer);
    }
}

```

I've tried defining the ThreadPoolTaskExecutor:

```
@Configuration
@EnableAsync
@EnableScheduling
public class AsyncConfig implements AsyncConfigurer {

    @Override
    public Executor getAsyncExecutor() {
        return new ThreadPoolTaskExecutor();
    }
}

```

It always times out after 30 seconds with a log;

```
12:14:28.028 [http-nio-8080-exec-2] DEBUG c.b.b.bof_static.config.BofStaticExceptionHandler - Async timeout for GET [/streamtest]
12:14:28.028 [http-nio-8080-exec-2] DEBUG org.springframework.web.servlet.DispatcherServlet - Null ModelAndView returned to DispatcherServlet with name 'dispatcherServlet': assuming HandlerAdapter completed request handling
12:14:28.028 [http-nio-8080-exec-2] DEBUG org.springframework.web.servlet.DispatcherServlet - Successfully completed request
12:14:28.030 [http-nio-8080-exec-2] DEBUG o.s.security.web.access.ExceptionTranslationFilter - Chain processed normally

```

I'm unable to find any other solutions. Can anyone point out what's missing?