A DESCRIPTION OF THE PROBLEM :
At the top of the page, it says:

"A URL pointing to the icon file, may be in one of the following formats: gif, jpg, png, ico."

Later on, it says:

"icon element: Contains an HTTP URL to an image file in either GIF or JPEG format."




URL OF FAULTY DOCUMENTATION :
http://download.oracle.com/javase/7/docs/technotes/guides/javaws/developersguide/syntax.html#information