When setting "jboss.as.jpa.vfs" property to false in persistence.xml PersistenceUnitInfo#getPersistenceUnitRootUrl() returns an Url that points to an empty folder (named "Contents"). The parent of this folder does holds the application jar.

file:/D:/Java/jboss-as-7.2.0.Alpha1/standalone/tmp/vfs/temp9c270668d311f0c4/vjpa_jboss_example.jar-7ef91a4c66eeff18/contents/

Observed this at PersistenceProvider#createContainerEntityManagerFactory() method call.