The rightClickEmpty event is fired whenever the player right clicks with an empty hand. It does not offer any special getters, but you can still access all members from MCPlayerInteractEvent
This class was added by a mod with mod-id
crafttweaker. So you need to have this mod installed if you want to use this feature.
Importing the class
It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import at the very top of the file.