Looking for an open-source Java Help API

I'm working on an application written in Java. I want to allow the user to read the "Help" of the application. I'm basically looking for a Java free open-source equivalent for Microsoft chm. I'd like it to have support for "Find" and tree-like structures. I am willing to write one component myself but I was wondering if existent alternatives already existed before attempting to reinvent the wheel... Are there any options available?