Just my opinion of course, but:

> What's the matter with this?

To me what makes this very "Java" is the arguments being passed, and all the OOP stuff that isn't providing any benefit and isn't really modeling real-world-ish objects (which IMHO is where OOP shines). .version(Version.HTTP_1_1) and .followRedirects(Redirect.NORMAL) I can sort of accept, but it requires knowing what class and value to pass, which is lookups/documentation reference. These are spread out over a bunch of classes. But we start getting so "Java" with the next ones. .connectTimeout(Duration.ofSeconds(20)) (why can't I just pass 20 or 20_000 or something? Do we really need another class and method here?) .proxy(ProxySelector.of(new InetSocketAddress("proxy.example.com", 80))), geez that's complex. .authenticator(Authenticator.getDefault()), why not just pass bearer token or something? Now I have to look up this Authenticator class, initialize it, figure out where it's getting the credentials, how it's inserting them, how I put the credentials in the right place, etc. The important details are hidden/obscured behind needless abstraction layers IMHO.

I think Java is a good language, but most modern Java patterns can get ludicrous with the abstractions. When I was writing lots of Java, I was constantly setting up an ncat listener to hit so I could see what it's actually writing, and then have to hunt down where a certain thing is being done and figuring out the right way to get it to behave correctly. Contrast with a typical Typescript HTTP request and you can mostly tell just from reading the snippet what the actual HTTP request is going to look like.

> What's the matter with this? It's a clean builder pattern

I feel like you answered yourself. Java makes you do this by not supporting proper keyword arguments.

The boilerplate of not having sane defaults. .NET is much simpler:

    using HttpClient client = new();
    HttpResponseMessage response = await client.GetAsync("https://...");
    if (response.StatusCode is HttpStatusCode.OK)
    {
        string s = await response.Content.ReadAsStringAsync();
        // ...
    }

Yeah this is all over Rust codebases too for good reason. The argument is that default params obfuscate behaviour and passing in a struct (in Rust) with defaults kneecaps your ability to validate parameters at compile time.