Implementing: javax.xml.bind.annotation.DomHandler

When a JAXB provider needs to unmarshal a part of a document into an infoset representation, it first calls this method to create a Result object.

A JAXB provider will then send a portion of the XML into the given result. Such a portion always form a subtree of the whole XML document rooted at an element.

Returns:  null if the operation fails. The error must have been reported to the error handler.