Uses of Class
org.bukkit.Instrument

Packages that use Instrument 
Package Description
org.bukkit
More generalized classes in the API.
org.bukkit.block
Classes used to manipulate the voxels in a world, including special states.
org.bukkit.entity
Interfaces for non-voxel objects that can exist in a world, including all players, monsters, projectiles, etc.
org.bukkit.event.block
Events relating to when a block is changed or interacts with the world.