The image lightbox doesn't work

After enabling the image lightbox from the Administration the result I get is:

• a black transparent square on top of the Applications panel
• hovering over an image from the page content doesn't show any toolbar

Checking the JavaScript console I noticed that both:

• /xwiki/webjars/wiki:xwiki/webjar-blueimp-gallery/css/blueimp-gallery.min.css
• /xwiki/webjars/wiki:xwiki/webjar-blueimp-gallery/js/blueimp-gallery-bundle.min.js

failed to be loaded. After further inspection it seems the org.xwiki.contrib:webjar-blueimp-gallery WebJar is not installed, although org.xwiki.platform:xwiki-platform-image-lightbox-webjar, which depends on it, is installed, and in fact a core extension.

The reason seems to be in https://github.com/xwiki/xwiki-platform/blob/xwiki-platform-14.1-rc-1/xwiki-platform-distribution/xwiki-platform-distribution-war-dependencies/pom.xml#L687

Make sure to not package contrib extensions since they need to remain upgradeable

Maybe the problem is that org.xwiki.platform:xwiki-platform-image-lightbox-ui was added as a dependency of xwiki-platform-distribution-ui-base instead of xwiki-platform-distribution-flavor-common? (which has some contrib deps that end-up installed correctly).