[lworld] RFR: 8372515: [lworld] Plumb in javac flags for compiling with preview mode [v4]

[David Beaumont]

On Wed, 26 Nov 2025 19:50:39 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> src/jdk.compiler/share/classes/com/sun/tools/javac/file/JRTIndex.java line 76:
>> 
>>> 74:     }
>>> 75: 
>>> 76:     private static class FileSystemResources {
>> 
>> Just moving all the outer class code into here. The actual changes are pretty small.
>> Mostly just the static management of the preview/non-preview versions and introduction of close semantics.
>
> This kind of refactoring is better done separately, making the intended change harder to review.

Doing so would slow this review down by at least a day. Are you okay with that given the time constraints. This change *isn't* just a "neatening up" of the code, there's key functionality here (since the relationship of JRTIndex instances to the underlying resources is moving from "one-to-one" to "many-to-one". I'll see about splitting this and all the closeable related changes up, but they need to go in before the rest of the plumbing.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1761#discussion_r2622569854