DisableItemMerge disables item merging by canceling every ItemMergeEvent. Item merging can also be disabled on spigot and spigot forks by setting world-settings.default.merge-radius.item in spigot.yml to 0, but it will not completely disable it because items that are on top of another will still get merged. Do not set merge-radius.item to negative numbers, it will flip the item being merged! DisableItemMerge works on bukkit and bukkit forks.
