RFR: 8356047: [macos] jpackage produces confusing post- and pre- installation PKG scripts [v8]

[Alexey Semenyuk]

On Wed, 8 Oct 2025 02:36:13 GMT, Alexander Matveev <almatvee at openjdk.org> wrote:

>> Let's address customizable resource logging in a separate patch. I filed [JDK-8369334](https://bugs.openjdk.org/browse/JDK-8369334) for this effort.
>
> I just fix it. Let me know what you think. I can revert my last commit.

It fixes one specific issue that just popped up. There may be more, but jpackage tests don't trap "null"-s in log messages emitted by OverridableResource.

The change to OverridableResource is wrong for a few reasons:
 - It unconditionally writes a log message; log messages in OverridableResource are created only when the destination file or output stream is not `null`. This change contradicts logging in OverridableResource.
 - It assumes that the set of resource sources is fixed. This assumption is wrong. It is possible to configure the order and the set of resource sources, see `OverridableResource.setSourceOrder()`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25510#discussion_r2412381007