RFR: 8317678: Fix up hashCode() for ZipFile.Source.Key [v8]

[Lance Andersen]

On Wed, 18 Oct 2023 15:59:13 GMT, Sean Coffey <coffeys at openjdk.org> wrote:

>> Fix up java.util.zip.ZipFile$Source hashCode() impl so that duplicate Source objects aren't created for the same zip file.
>
> Sean Coffey has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update lastModifiedTime comment

Marked as reviewed by lancea (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/16115#pullrequestreview-1685516723