RFR: 8240903: Add test to check that jmod hashes are reproducible [v5]

[Alan Bateman]

On Wed, 30 Mar 2022 01:55:30 GMT, Dongbo He <dongbohe at openjdk.org> wrote:

>> This creates a regression test for [JDK-8240734](https://bugs.openjdk.java.net/browse/JDK-8240734). This was once blocked 
>> by a time stamp issue which has been resolved by: [JDK-8276766 ](https://bugs.openjdk.java.net/browse/JDK-8276766)
>> 
>> We found the issue can be produced stably with at least 64 modules.
>> Note that we need to add the --date jmod option to avoid the timestamp issue.
>> 
>> Testing:
>> Added test case fails without fix for JDK-8240734, and passes otherwise.
>> Tested with tier2 on linux x86.
>
> Dongbo He has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
> 
>  - Merge branch 'master' into 8240903
>  - Delete extra blank links
>  - Change shell test io java test
>  - Get date by 'date +%Y-%m-%dT%H:%M:%S%:z'
>  - Update Copyright
>  - 8240903: Add a regression test for JDK-8240734

Thanks for the timings. I mostly asked because we've had issues with I/O heavy tests on older macOS tests in our CI. Several tests have had to be dialled down or configured to run with very large timeouts. We'll have to see how this one fares.

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PR: https://git.openjdk.java.net/jdk/pull/7948