RFR: 8365467: Fix multiple issues in ExplodedImage [v2]

[Alan Bateman]

On Fri, 29 Aug 2025 08:49:27 GMT, David Beaumont <duke at openjdk.org> wrote:

>> This PR addresses several issues found while adding unit tests for ExplodedImage.
>> I have added review comments for changes (some of which are a little preferential, but bring the code into line with things like ImageReader in terms of the name choices for variables).
>> Later it is likely that this code will be adapted for the up-coming preview mode support in Valhalla, so having it unit-testable is important.
>
> David Beaumont has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Feedback tweaks.

Just some context here. jrtfs has support for exploded images so that it can be used (by javac) in the JDK build. This code is not used once the JDK images are built. It's very likely that some of this code is never executed as javac only uses a subset of the file system API. So good to have tests for this as it would other be untested/unused and bugs will hide until the day that javac expands its usage and hits them.

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PR Comment: https://git.openjdk.org/jdk/pull/26757#issuecomment-3236421584