persistence.xml in EAR/META-INF folder with <jar-file>

adding persistence.xml in META-INF dir of an ear like this
?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="mypersistencunit">
...
<jar-file>lib/myjpa.jar</jar-file>

result in exception:
Caused by: java.lang.RuntimeException: error trying to scan <jar-file>: vfs:/c:/JBoss/jboss-as-7.0.0.Final/bin/content/lib/myjpa.jar