I don't know if you remember it, but a while ago we have decided to
switch from GPL to LGPL.
Changes in headers have never been done. So I start to do it
yesterday. Before I need your opinion on some rules:
• You give you credit to XpertNet. If you give to XpertNet your
credit, it's simple for XpertNet to manage licensing issues. We can't
give the credit to XWiki, because it's not an entity, and I don't
think ObjectWeb accept credit.
• We can use the javadoc tag @author for putting your name on. Or
simply a contributors.txt on the root of the svn, a page on the wiki,
on the Jira's task and the SVN (because you commit it).