Using JNDI Connection pool as Datanucleus PersistenceManagerFactory - glassfish

Question

I am developing a web application using DataNucleus as DAO layer (mainly due to historical reasons). It runs inside Payara server (a Glassfish 4 fork)
It works fine, but now I'd like to use a JNDI db connection pool to obtain the PersistenceManagerFactory for DataNucleus.
From the documentation, it seems that the following code would suffice:
pmf = JDOHelper.getPersistenceManagerFactory( "jdbc/HxWmDb", context );
but this way I obtain an error starting the application (DbSession is the class which implements the DAO layer, and the error line is exactly the one above):
Caused by: java.lang.ClassCastException
at com.sun.corba.ee.impl.javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:262)
at javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:150)
at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:1791)
at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:1755)
at ejb.DbSession.<init>(DbSession.java:119)
...
Caused by: java.lang.ClassCastException: com.sun.gjc.spi.jdbc40.DataSource40 cannot be cast to org.omg.CORBA.Object
at com.sun.corba.ee.impl.javax.rmi.PortableRemoteObject.narrow(PortableRemoteObject.java:245)
Any suggestion?
Little update, as requested by DN1:
As a first approach, I tried exactly what is described in the link:
Properties properties = new Properties();
properties.setProperty("datanucleus.ConnectionFactoryName","jdbc/HxWmDb");
PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory(properties);
And the error is, as already said, that a URI is anyway required:
Caused by: org.datanucleus.exceptions.NucleusException: You haven't specified persistence property 'datanucleus.ConnectionURL'