RFR: 8369812: HttpClient doesn't handle H3_REQUEST_REJECTED correctly [v4]

[Daniel Fuchs]

On Tue, 14 Oct 2025 13:54:26 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review of this change which proposes to fix the implementation in HttpClient to correctly handle the H3_REQUEST_REJECTED error code?
>> 
>> As noted in https://bugs.openjdk.org/browse/JDK-8369812, the current implementation in the HttpClient treats this like an error and causes the HTTP request to fail. The proposed change in this PR addresses this by marking a request which was reset due to H3_REQUEST_REJECTED as unprocessed. This then allows the `MultiExchange` to reissue the request afresh. This new behaviour matches the expectation specified for this error code in the HTTP/3 RFC.
>> 
>> A new jtreg test has been introduced to reproduce the issue and verify the fix.
>
> Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Daniel's review - use POST instead of GET

Marked as reviewed by dfuchs (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27793#pullrequestreview-3335953859