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

Instructs JAXB 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 JAXB users, as it JAXB 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, JAXB implementations will be able to correctly bind Dog and Cat.