RFR: 8304911: Use OperatingSystem enum in some modules [v2]

[Alan Bateman]

On Wed, 5 Apr 2023 14:18:54 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> Created [JDK-8305662](https://bugs.openjdk.org/browse/JDK-8305662) to track refactoring.
> Will revert.

Thanks, you can revert the qualified export in module-info and the additional grant in default.policy too.

The interesting thing about this PR is that each change begs the question on whether the code should be refactored, that would take time of course.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13335#discussion_r1158609098