public abstract ResultT createUnmarshaller (ValidationEventHandler errorHandler)

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.

errorHandler     if any error happens between the invocation of this method and the invocation of getElement(Result), they must be reported to this handler. The caller must provide a non-null error handler. The Result object created from this method may hold a reference to this error handler.

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