This annotation adds information that would be available from a schema type, but isn't implied by a Java class declaration. The annotation has several attributes:

• factoryClass and factoryMethod define the class containing a no-argument method for creating an instance of this class as the equivalent of an empty XML element.
• The attribute name provides the XML schema name if you don't want to use the class name.
• The namespace attribute provides the name of the target namespace.
• The string array value defined by propOrder establishes an ordering of the sub-elements. (It's pretty obvious that there can't be a connection between the textual order of items in a class definition and the order its fields are returned by reflection methods.)

@XmlRootElement
@XmlType( propOrder={ "title", "items", "cluster" } )
public class Document {
    ...
}