@Target(value=TYPE)
 @Retention(value=RUNTIME)
public @interface XmlSeeAlso

Instructs Jakarta XML Binding to also bind other classes when binding this class.

Java makes it impractical/impossible to list all sub-classes of a given class. This often gets in a way of Jakarta XML Binding users, as it Jakarta XML Binding cannot automatically list up the classes that need to be known to JAXBContext.

For example, with the following class definitions:

 class Animal {}
 class Dog extends Animal {}
 class Cat extends Animal {}
 

The user would be required to create JAXBContext as JAXBContext.newInstance(Dog.class,Cat.class) (Animal will be automatically picked up since Dog and Cat refers to it.)

XmlSeeAlso annotation would allow you to write:

 @XmlSeeAlso({Dog.class,Cat.class})
 class Animal {}
 class Dog extends Animal {}
 class Cat extends Animal {}
 

This would allow you to do JAXBContext.newInstance(Animal.class). By the help of this annotation, Jakarta XML Binding implementations will be able to correctly bind Dog and Cat.