Uniquely identifies of an entity instance in a particular Session by identifier. Note that it's only safe to be used within the scope of a Session: it doesn't consider for example the tenantId as part of the equality definition.
Information used to determine uniqueness consists of the entity-name and the identifier value (see {@link #equals}).
Performance considerations: lots of instances of this type are created at runtime. Make sure each one is as small as possible by storing just the essential needed.
@author Gavin King
@author Sanne Grinovero