The name of the method has a special meaning if (and only if) the
For instance, a Parent Copy for the attribute
The type returned by the method must be the same as the type of the attribute.
A Parent Copy automatically copies the specified attribute from the parent object into the specified attribute, any time the parent is attached to the child.
Assume that you have two classes: Lineitem and Product, with Product being a parent of Lineitem.
Let's assume that Lineitem has an attribute named productPrice, and that we have defined a Parent Copy for that attribute, so that it copies the Product's price attribute.
If a Lineitem has no Product, then as soon as one is assigned to it, that Product's price will be copied into it.
If a Lineitem already has a Product, and a different Product is assigned to it, that Product's price will be copied into the Lineitem.
If a Lineitem already has a product, and that Product is removed, leaving the Lineitem without a Product, nothing happens.
A Parent Copy method may have code in it. If so, that code will be invoked, but that is meant only as a debugging tool. The code should not modify the object, or any other persistent object.