Uses of Enum Class

Packages that use EntityType
The root package of the Bukkit API, contains generalized API classes.
Classes used to manipulate the voxels in a world, including special states.
Interfaces for non-voxel objects that can exist in a world, including all players, monsters, projectiles, etc.
Events relating to entities, excluding some directly referencing some more specific entity types.
Events relating to players.
The interfaces used when manipulating extra data can can be stored inside item stacks.
Classes that represents various voxel types and states.