See https://studio.atlassian.com/source/cru/CR-AOD-437#c33300

Should also refactor the code.

I had a stab at this on the weekend. It will involve updating osgi imported and exported packages, and will be made easier by making the studio-theme-core library a plugin and putting the com.atlassian.extras.api package in there as an export (and an import, and a bundled jar - I haven't looked into whether it is bundled in each app yet).

The main sticking point seems to be in Confluence where it has trouble loading the classes.