docs: public Object getObjectInstance(Object obj, Name name, Context nameCtx,
        Hashtable<?, ?> environment) throws Exception {
      Reference ref = (Reference) obj;
      String className = ref.getClassName();
      if (className.equals("org.postgresql.xa.PGXADataSource")) {
        return loadXADataSource(ref);
      } else {
        return null;
      }
    }