HasContentId is kind of an analogue to the Java class Object for content
addressable data; everything content addressable should implement it.
Two HasContentId instances are equal if and only if
Nested Class Summary
Nested classes/interfaces inherited from interface org.baseparadigm.i.HasAs
Sometimes a content addressable object will be mutable until it is
finished being constructed. getId() should make it immutable because
comparing content is done based on ID and changing IDs messes
with natural ordering.