Transient Composite Type.
 TransientComposites have the following criteria;
 
 - Does not persist its state, and is not serializable
 
 - Can not be referenced from Properties, Associations, ValueComposites nor Entities
 
 - Can reference all types
 
 - No lifecycle
 
 - equals/hashCode is delegated to a single Mixin implementing the methods, like any other method