Greetings and welcome to the community forum!
This isn't a legal opinion, but as I understand it, (almost) every piece of OO is under the Apache license, which allows you to do just about anything you want. I believe the only requirements are that you acknowledge the source of the material and make available a copy of the Apache license. I can't say if the same requirements would apply to using only a small part of the OO material.
You can read about the license here:
http://en.wikipedia.org/wiki/Apache_License
http://www.apache.org/foundation/license-faq.htmlI believe there is a mailing list to ask questions about using Apache-licensed material; check on the apache.org site.
So
check what license applies to the material you want to use, and, of course, if you feel you need a reliable answer, buy a legal opinion from a qualified lawyer.