qdoc extraimages.HTML not supported

This says the config is HTML.extraimages
https://doc.qt.io/qt-6/qdoc-guide-conf.html#extra-files

This says it is extraimages.HTML
https://doc.qt.io/qt-6/22-qdoc-configuration-generalvariables.html#extraimages

The general syntax is extraimages.format = image

In my tests, HTML.extraimages works and copies the images to the output and extraimages.HTML does nothing.

Looking at the source, it appears that all of stylesheets, scripts and extraimages should have the format as a prefix, not a suffix:
https://github.com/qt/qttools/blob/2bd7f9f0bfb5a7754c361e17dbaf0b8c44b262c6/src/qdoc/qdoc/generator.cpp#L1744-L1746