<versions> <version groupId="com.mycompany" version="2.0"/> <version groupId="com.someother" artifactId="foo" version="3.0"/> </versions>
This allows you to lock artifacts to a specific version. Modules referring to another version of this artifact in their classloader.xml will not get the requested version. They will get the version specified in versions.xml instead.
This is useful when you have a module which refers to a framework artifact: You don't want to be forced to repackage the module (i.e. update its classloader.xml) everytime you upgrade the framework artifact.
Note that using this means that you have to make sure all your modules are compatible with the specified versions.