RFR: 8266835: Add a --validate option to the jar tool [v3]

[Jorn Vernee]

On Tue, 8 Jun 2021 18:32:36 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> This patch adds a `--validate` option to the jar tool which can be used to validate a jar file that might be malformed. For instance, if a jar is a multi-release jar, it is malformed if different versions expose different APIs.
>> 
>> The implementation is straight forward since there already exists validation logic that is run when creating or updating a jar. This patch just exposes that logic directly under a new command line flag.
>> 
>> I've enhanced the existing ApiValidatorTest to also create malformed jars using the zip file APIs (the jar tool does not output malformed jars) and run them through `jar --validate`.
>> 
>> Note that while the jdk's jar tool does not output malformed jars, third-party archiving tools might, or the jar could have been manually edited.
>> 
>> Some prior discussion here: https://mail.openjdk.java.net/pipermail/core-libs-dev/2021-May/077420.html
>> 
>> Testing: running jdk/tools/jar test suite locally, tier 1-3 (in progress), manual testing.
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Improve help message.

If the changes look good like this, please review the accompanying CSR for the command line option changes: https://bugs.openjdk.java.net/browse/JDK-8267402

Thanks

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PR: https://git.openjdk.java.net/jdk/pull/3971