RFR: 8301302: Platform preferences API [v5]

[Michael Strauß]

On Tue, 5 Sep 2023 23:27:51 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> is it actually possible to have keys removed at runtime?
>
> The set of preferences that is reported by a platform is hard-coded in the native platform implementation, and depends on the operating system version. It might indeed be the case that an OS upgrade/downgrade could result in a different set of reported properties, but can this happen while a JavaFX applications remains running?
> 
> In any case, even if that were to happen, the current behavior is that a preference that was once reported will not be removed.

Looks like I spoke too soon. Mappings can actually be removed at runtime, one such example is `Windows.SPI.HighContrastColorScheme`, which is only available if `Windows.SPI.HighContrast` is `true`.

This doesn't change the `ChangedValue` implementation, and there are tests that cover the key removal scenario.

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/1014#discussion_r1319364873