This is a library that allows you to write plugins that support bukkit, bungee, and nukkit all in the same jar. By wrapping all player instances your plugin is never directly exposed to any server api (the option is still there though!) All plugins are loaded the same way bukkit loads them, with a custom yml in the jar file.
See the github wiki for a bare bones plugin example.
More information will pour into this and the wiki!
Wanna contribute? Edit the github wiki or make a pull request with your code!