Edit XML file using JDOM

[DECAGON]

I want to add \[code\]xmlns:atom\[/code\] to the root element of an XML file, the file already exists, I just want to modify it by adding the adding \[code\]xmlns\[/code\]. The rest of the files is to be left unchanged. As an example, I have \[code\]<rss version="2.0">\[/code\] in file and I want to convert it in to \[code\]<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">\[/code\] using JDOM. How can I do this?