Resteasy Reactive adds transfer-encoding header though content-length is present

[Postremus]

Describe the bug

I want to stream filedownloads. The filesize is already known (stored in db on upload).
The filesize is important to me, since I can use it as content-length header, which allows the browser to show a progress bar for the download instead of just spinning.

e.g.

Without the content-length header, browser would simply show a spinning progress.

In resteasy-classic, this worked without problems.
In resteasy-reactive however, I found that the "Transfer-Encoding: Chunked" header is always added to the response when I am stream, even though I manually set content-length.

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public Response hello() {
        String longText = String.join(";", Collections.nCopies(10000000, UUID.randomUUID().toString()));

        byte[] bytes = longText.getBytes(StandardCharsets.UTF_8);

        return Response.ok(new ByteArrayInputStream(bytes), "text/plain")
                .header("Content-length", bytes.length)
                .build();
    }

According to the RFC 2616, this behaviour is not allowed.

Messages must not include both a Content-Length header field and a non-identity transfer-coding. If the message does include a non-identity transfer-coding, the Content-Length must be ignored.

https://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.4.4

Expected behavior

No Transfer-Encoding header is present if a content-length was already manually set.
The response should still be streamed.

Actual behavior

How to Reproduce?

Reproducer:
transfer-encoding-clash.zip

1. mvn quarkus:dev
2. Open a Browser and the network tools to see response headers
3. Visit http://localhost:8080/hello
4. Inspect the response. With resteasy-reactive, it contains both transfer-encoding and content-length.
5. Change dependency resteasy-reactive to resteasy classic.
6. Visit http://localhost:8080/hello. Only content-length is now present in the response

Output of uname -a or ver

Microsoft Windows [Version 10.0.19044.1766]

Output of java -version

openjdk 18.0.1 2022-04-19 OpenJDK Runtime Environment Temurin-18.0.1+10 (build 18.0.1+10) OpenJDK 64-Bit Server VM Temurin-18.0.1+10 (build 18.0.1+10, mixed mode, sharing)

GraalVM version (if different from Java)

No response

Quarkus version or git rev

2.10.1.Final

Build tool (ie. output of mvnw --version or gradlew --version)

Apache Maven 3.8.4 (9b656c72d54e5bacbed989b64718c159fe39b537) Maven home: C:\eclipse\tools\java\maven Java version: 18.0.1, vendor: Eclipse Adoptium, runtime: C:\eclipse\tools\java\18 Default locale: de_DE, platform encoding: UTF-8 OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

Additional information

No response

[quarkus-bot]

/cc @FroMage, @geoand, @stuartwdouglas

[geoand]

Thanks for the reproducer. I totally agree the behavior is not correct, looking into it now

[geoand]

#26467 takes care of the issue