Extension handlers are non-required interfaces in the
org.xml.sax.ext package.
To set the
LexicalHandler
for an XML reader, set the property
http://xml.org/sax/handlers/LexicalHandler.
To set the
DeclHandler
for an XML reader, set the property
http://xml.org/sax/handlers/DeclHandler.
If the reader does not support the requested property, it will throw a
SAXNotRecognizedException or a SAXNotSupportedException.