RFR: 8356575: Test order in which jpackage fills app image [v3]

[Alexander Matveev]

On Fri, 17 Oct 2025 17:07:41 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

>> - Test order in which jpackage fills app image
>> - Fix an issue with jpackage that it would fail to overwrite existing files in the app image. Uncovered by the test.
>
> Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use Files.mismatch() to check if the content of two files mismatch or not. Add TKit.assertMismatchFileContent() and TKit.assertSameFileContent() helper functions.

Looks good.

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Marked as reviewed by almatvee (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27826#pullrequestreview-3352312824