Not required if you're using any of spigot's forks like paper or purpur, fixes console errors and the lack of items dropped from mining and farming. You'll see a new option in the main config (config.yml) is_spigot, set this to true if you are using spigot and it will cause the plugin to handle item dropping itself so the error is avoided. it's not the best solution, but spigot doesn't allow me to edit item drops (weirdly i can only remove items, adding items will cause the error) but this is not the case in its forks