code: public List<PersistenceUnit<PersistenceDescriptor>> getAllPersistenceUnit()
     {
        List<PersistenceUnit<PersistenceDescriptor>> list = new ArrayList<PersistenceUnit<PersistenceDescriptor>>();
        List<Node> nodeList = model.get("persistence-unit");
        for(Node node: nodeList)
        {
           PersistenceUnit<PersistenceDescriptor>  type = new PersistenceUnitImpl<PersistenceDescriptor>(this, "persistence-unit", model, node);
           list.add(type);
        }
        return list;
     }
docs: Returns all <code>persistence-unit</code> elements
  @return list of <code>persistence-unit</code>