Spring Redirect is not followed on 301 with default RestClient

Default RestClient does not follow redirect (in case of 301 at least. Response body is null

@RestController
class SampleController {

    @GetMapping("/first")
    fun redirectToSecond() = ResponseEntity
        .status(301)
        .header("Location", "/second")
        .build<Unit>()

    @GetMapping("/second")
    fun noRedirect() = "OK"
}

@Component
class Runner(
    @Value("\${server.port}")
    private val port: Int
) : ApplicationRunner {

    override fun run(args: ApplicationArguments?) {
        // this works: redirect is followed
        val entityWithRC = RestClient.builder(RestTemplate()) // <---- this
            .baseUrl("http://localhost:$port")
            .build()
            .get()
            .uri("/first")
            .retrieve()
            .toEntity<String>()

        // this does not work: redirect is not followed
        val entityWithDefaults = RestClient.builder()
            .baseUrl("http://localhost:$port")
            .build()
            .get()
            .uri("/first")
            .retrieve()
            .toEntity<String>()

        println(entityWithRC)
        println(entityWithDefaults)
    }
}

````
Console output:

<200 OK OK,OK,[Content-Type:"text/plain;charset=UTF-8", Content-Length:"2", Date:"Thu, 17 Oct 2024 14:39:00 GMT", Keep-Alive:"timeout=60", Connection:"keep-alive"]> <301 MOVED_PERMANENTLY Moved Permanently,[content-length:"0", date:"Thu, 17 Oct 2024 14:39:00 GMT", location:"/second"]>

**Comment From: bclozel**

Thanks for getting in touch. This behavior is by design.

`RestTemplate` will use by default the `SimpleClientHttpRequestFactory` (backed by `java.net.HttpURLConnection`), while the more recent `RestClient` is using by default the `JdkClientHttpRequestFactory` (backed by `java.net.http.HttpClient`).

In this case, `java.net.HttpURLConnection` and `java.net.http.HttpClient` have different behavior when it comes to following redirects. As a framework, our best option is to rely as much as possible on the clients defaults and not try to align all clients on a single behavior (it's impossible and it would be surprising to many).

You can get the behavior you want by configuring the request factory like this:

```java
HttpClient httpClient = HttpClient.newBuilder().followRedirects(HttpClient.Redirect.NORMAL).build();
RestClient restClient = RestClient.builder().requestFactory(new JdkClientHttpRequestFactory(httpClient)).build();