Why can't I find the API documentation for com.sun.* classes in rt.jar?

I found a scenario that uses com.sun.jndi.toolkit.UrlUtil class in a source cods. I can find this class in rt.jar in Standard Java Dis开发者_运维百科tribution. But I cannot find any API documentation for classes in this package. Why these classes are hidden? Are there any drawbacks in using those classes in my code?

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Because com.sun.* is not an API. It's Sun's implementation. You shouldn't rely on these classes, because they are likely to change.

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Altavista found this one

http://www.docjar.com/docs/api/sun/misc/package-index.html

It's not official, but may help...