code: public <T> T unwrap(Class<T> cls) // d706751
      {
          if (cls.isInstance(ivFactory))
          {
              return cls.cast(ivFactory);
          }
  
          throw new PersistenceException(cls.toString());
      }
docs: Return an object of the specified type to allow access to
  provider-specific API.
  
  @param cls the class of the object to be returned
  @return an instance of the specified class
  @throws PersistenceException if the class is not supported