RFR: 8350279: HttpClient: Add a new HttpResponse method to identify connections [v12]

[Daniel Fuchs]

On Tue, 8 Apr 2025 19:27:17 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

>> Adds `HttpResponse::connectionLabel` method that provides an identifier for the connection.
>> 
>> **Implementation note:** The feature is facilitated by `HttpConnection::label`, which should not be confused with `HttpConnection::id`. This distinction is explained in the JavaDoc of both properties.
>
> Volkan Yazici has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add `@implNote` to state that the built-in is always non-empty

Marked as reviewed by dfuchs (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/24154#pullrequestreview-2753073405