By downloading the source release and running Javadoc on that package.
We do not publish documentation on any of the sun.* packages,
so you must create it yourself.
For more details, see:
http://java.sun.com/products/jdk/faq.html#A12
The source release can be found at:
http://java.sun.com/j2se/javadoc/faq.html#sourcecode
-Doug Kramer
Javadoc team