public void parse(InputStream stream, ContentHandler handler, Metadata metadata,
                      ParseContext context) throws SAXException, IOException, TikaException {
        getDelegateParser(context).parse(stream, handler, metadata, context);
    }
Looks up the delegate parser from the parsing context and
delegates the parse operation to it. If a delegate parser is not
found, then an empty XHTML document is returned.
<p>
Subclasses should override this method to parse the top level
structure of the given document stream. Parsed sub-streams can
be passed to this base class method to be parsed by the configured
delegate parser.
tika-core/src/main/java/org/apache/tika/parser/DelegatingParser.java