[crac] RFR: 8350845: [CRaC] Support C/R engines in form of a library [v2]

[Timofei Pushkin]

On Wed, 5 Mar 2025 09:33:52 GMT, Timofei Pushkin <tpushkin at openjdk.org> wrote:

>> The engine is not interpreting JVM options; engine receives its programmatic configuration and has to deal with that. JVM defines the user API and we can decide that repeated use of the same argument is prohibited (as that would be more likely an user error).
>
> I mean that an engine can interpret reconfiguration of the same key not as overwriting of the previous value but somehow differently, e.g. as concatenation in my example (overwriting is always possible by re-creating the whole conf if needed). Since the VM is just passing the keys through I would leave the interpretation up to the engine. But it's not a strong opinion, I can move the warning to JVM if you still think it would be better.

After thinking a bit more, yes, let's move the warning to JVM to simplify the engine implementation. We can always remove the warning if we find a sensible use case for repeating keys.

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PR Review Comment: https://git.openjdk.org/crac/pull/207#discussion_r1981092974