Represents an XML tag name (and attributes for start tags.)
This object is used so reduc
e the number of method call parameters among unmarshallers. An instance of this is expected to be reused by the caller of XmlVisitor. Note that the rest of the unmarshaller may modify any of the fields while processing an event (such as to intern strings, replace attributes), so XmlVisitor should reset all fields for each use.
The 'qname' parameter, which holds the qualified name of the tag (such as 'foo:bar' or 'zot'), is not used in the typical unmarshalling route and it's also expensive to compute for some input. Thus this parameter is computed lazily. @author Kohsuke Kawaguchi