RFR: 8336844: ZipConstants64 defines duplicate constants EXTID_ZIP64 and ZIP64_EXTID

[Jaikiran Pai]

On Fri, 19 Jul 2024 19:35:14 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

> This change deduplicates constants in ZipConstants64 for the Zip64 Extended Information Extra Field Header ID (see APPNOTE.TXT 4.5.3).
> 
> I think there are arguments for consolidating on either `EXTID_ZIP64` or `ZIP64_EXTID`. The PR currently consolidates on `EXTID_ZIP64`, `ZIP64_EXTID` is also an option if there's a preference for that.
> 
> I noticed this while working on a zip64 bug in [JDK-8328995](https://bugs.openjdk.org/browse/JDK-8328995), I was reviewing places that handled zip64 extra fields and initially missed some because I was only looking at one of the constants.

Hello Liam, the changes look fine to me. Choosing `EXTID_ZIP64` constant in preference of the other seems OK too, since that constant is more closer in code location with the other extra field header ids.

Some of these files require a copyright year update. Please update those before integrating.

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Marked as reviewed by jpai (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20264#pullrequestreview-2189609923