For those who might be interested in PluginManager feature from WebLaF core – its tutorial is now available in WebLaF Wiki on GitHub.

PluginManager is a large feature that was added into WebLaF library core with v1.28 update. It provides a simple and convenient way to load, store and use plugins within your application. It also handles lots of possible load problems and provides tools to filter out unwanted plugins and a lot more…

There are also some other tutorials there which you may find useful.
Follow this link to see the full list: https://github.com/mgarin/weblaf/wiki