IReferenceHandler
A reference handler can store and resolve references
of mapping target objects.
Stores the created target instance.
Called by Mapperly just after a new target object instance is created.
Before an object is created by Mapperly this method is called.
It can attempt to resolve existing target object instances based on the source object instance.
If false is returned, Mapperly creates a new instance of the target class.
If true is returned, target has to be non-null.
Mapperly then uses the target instance.