RFR: 8068958: Timestamp.from(Instant) should throw when conversion is not possible

[Eamonn McManus]

On Thu, 21 Dec 2023 21:51:10 GMT, Eamonn McManus <emcmanus at openjdk.org> wrote:

> Multiplying with `*` never produces `ArithmeticException`, so the catch in the existing code is never triggered. `Math.multiplyExact` does produce `ArithmeticException` if the multiplication overflows. So we can use that, and rethrow `IllegalArgumentException` as the specification says.
> 
> There is a small compatibility risk, in that code may have been relying on the previous silent overflow, and will now get an exception. But an exception is surely better than the nonsense results that overflow produces.
> 
> Thanks to Kurt Kluever for the test cases.

I think the three overflow cases we have are probably enough? (Just too big, as big as possible, as small as possible.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/17181#discussion_r1434585279