RFR: 8276766: Enable jar and jmod to produce deterministic timestamped content [v14]

[Andrew Leonard]

On Wed, 1 Dec 2021 18:20:11 GMT, John Neffenger <jgneff at openjdk.org> wrote:

> I'm testing it now. So far, it's working great!
> 
> I found one boundary problem. The magic instant of `1980-01-01T00:00:00Z` triggers an extended header with the wrong time:
> 
> ```
>   file last modified on (DOS date/time):          1980 Jan 1 00:00:00
>   file last modified on (UT extra field modtime): 1980 Jan 1 00:00:00 local
>   file last modified on (UT extra field modtime): 1980 Jan 1 08:00:00 UTC
> ```
> 
> One second later `1980-01-01T00:00:01Z` works fine (considering the rounding down to even seconds):
> 
> ```
>   file last modified on (DOS date/time):          1980 Jan 1 00:00:00
> ```

Thanks John. The 1980-01-01T00:00:00Z is a known issue because the zip xdostime format uses that value as the "marker" for date before-1980. I can adjust the --date value validation to be >  1980-01-01T00:00:00Z ?

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PR: https://git.openjdk.java.net/jdk/pull/6481