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

[Chen Liang]

On Fri, 21 Mar 2025 13:45:24 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.

This new API returns an `Optional`.

1. Can users make any assumption about the connection identity when it is empty? Such as assuming such connections are all the same (as implied by your use of `orElse(null)` in tests) or all different?
2. If we cannot make any assumption about the empty return value, can users make any assumption that a `HttpResponse` obtained from the JDK built-in `HttpClient` always return non-empty for the label?

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PR Comment: https://git.openjdk.org/jdk/pull/24154#issuecomment-2746061424