JDK-8283544 addressed the issue where HttpClient was adding a Content-Length: 0 request header for a GET request. The test/jdk/java/net/httpclient/ContentLengthHeaderTest.java, which was added as part of that fix, continues to reproduce the original issue if it is changed to issue the GET request as follows:

diff --git a/test/jdk/java/net/httpclient/ContentLengthHeaderTest.java b/test/jdk/java/net/httpclient/ContentLengthHeaderTest.java
index 0ff21c23a8f..16b117b8a66 100644
--- a/test/jdk/java/net/httpclient/ContentLengthHeaderTest.java
+++ b/test/jdk/java/net/httpclient/ContentLengthHeaderTest.java
@@ -142,7 +142,7 @@ public void getWithNoBody(Version version, URI uri) throws IOException, Interrup
         testLog.println(version + " Checking GET with no request body");
         HttpRequest req = HttpRequest.newBuilder()
                 .version(version)
- .GET()
+ .method("GET", HttpRequest.BodyPublishers.noBody())
                 .uri(uri)
                 .build();
         HttpResponse<String> resp = hc.send(req, HttpResponse.BodyHandlers.ofString(UTF_8));

This ends up generating a request which has the following request headers:

INFO: HEADERS: REQUEST HEADERS:
  GET /no_body HTTP/1.1
    Content-Length: 0
    Host: 127.0.0.1:12345
    User-Agent: Java-http-client/26-internal

### Why is this an HTTP/1.1-only problem?

HTTP/2 and HTTP/3 implementations of `HttpClient` already add the `Content-Length` header iff it is greater than zero:

https://github.com/openjdk/jdk/blob/4728f746a89ca7cb787b3d9969f09a80cc92f502/src/java.net.http/share/classes/jdk/internal/net/http/Stream.java#L906-L908
https://github.com/openjdk/jdk/blob/4728f746a89ca7cb787b3d9969f09a80cc92f502/src/java.net.http/share/classes/jdk/internal/net/http/Http3ExchangeImpl.java#L388-L390

They do this, unlike the `POST` and `PUT` exemption for HTTP/1.1 in the proposed PR, for all methods.
This behavior difference between HTTP/1 and HTTP/{2,3} is not a problem because

1. HTTP/2 and HTTP/3 are implicitly chunked when `Content-Length` is missing.
2. `Content-Length` is always optional for HTTP/2 and HTTP/3, for all methods. A user agent may add it, in which case it must match the total number of bytes sent in the body request.