public Enumeration<URL> getResources(String descriptorPath)  throws IOException{
	if(descriptorPath.equals("META-INF/persistence.xml")){
		String s = jar.getAbsolutePath().replace('\\', '/');
		final URL jarUrl = new URL("jar","",-1,"file:/"+s+"!/META-INF/persistence.xml");
		return new Enumeration<URL>() {
			private int position = 0;
			public boolean hasMoreElements() {
				return position>=0;
			}
			public URL nextElement() {
				if(position<0)
					throw new NoSuchElementException();
				position --;
				return jarUrl;
			}
		};
	}else{
		return super.getResources(descriptorPath);
	}
}