[jdk24u] Integrated: 8347334: JimageDiffGenerator code clean-ups

[Severin Gehwolf]

On Thu, 16 Jan 2025 15:52:55 GMT, Severin Gehwolf <sgehwolf at openjdk.org> wrote:

> Clean backport of some code clean-up for [JDK-8346239](https://bugs.openjdk.org/browse/JDK-8346239) which got recently backported to 24.0.1 as well.
> 
> Adds a test and improves code quality.

This pull request has now been integrated.

Changeset: 44000a9c
Author:    Severin Gehwolf <sgehwolf at openjdk.org>
URL:       https://git.openjdk.org/jdk24u/commit/44000a9ce23e34b3710e9b21ebf79c78684df624
Stats:     354 lines in 2 files changed: 327 ins; 14 del; 13 mod

8347334: JimageDiffGenerator code clean-ups

Backport-of: 63cedaf40e179267d75445a4c71ec15f29979cd3

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PR: https://git.openjdk.org/jdk24u/pull/21