JBoss is releasing binary versions of concurrent.jar which is partially copyrighted by Sun, see the license at <http://g.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/sun-u.c.license.pdf>. Unfortunately that is a 'non-transferable' license and the sublicensing clause is quite restricted. This license is probably not open source and not compatible with the LGPL.

This can be easily solved by dropping concurrent.jar and switching to java.util.concurrent which is available from Sun, OpenJDK and classpath. That is even recommended by Doug Lea.

Cheers,
Torsten