Override CSS aggregation to ensure correct file URL altering for files referenced by CSS files
>>> [!note] Migrated issue
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<!-- Migrated from issue #1428530. -->
Reported by: [mr.baileys](https://www.drupal.org/user/383424)
>>>
<p>We tried to blacklist *.woff files when investigating <span class="drupalorg-gitlab-issue-link drupalorg-gitlab-link-wrapper"><a href="https://git.drupalcode.org/project/cdn/-/work_items/982188" class="drupalorg-gitlab-link">https://git.drupalcode.org/project/cdn/-/work_items/982188</a></span>, but the blacklist had no effect. Looking closer, it seems that for resources in CSS files:</p>
<ul>
<li>Black-/white-listing has no effect.</li>
<li>The resources in those files inherit the stylesheet's UFI and ignore the ones defined in CDN</li>
</ul>
<p>To demonstrate, use the following Unique file identifier generation:</p>
<pre>*.css|drupal_cache<br>*.png|mtime</pre><p>All .png files from stylesheets will be served with a "drupal_cache:xxx" UFI instead of an "mtime:xxx" UFI.</p>
<p>(might be a documentation issue instead of a bug)</p>
issue