Bukkit/CraftBukkit — comment on commit dead73055e5cf3e7f0fb2f2e9b768194c2c8d14d
File:  line 0
By rmichela:

The MetadataStore interface is in Bukkit. The implementations are in CraftBukkit. The individual implementations are not in the public API because their details are not important to how the metadata framework operates and users of the framework never need to touch these classes. No sense polluting a public API with internal implementation classes.