code: public void initializeSession()
      {
          ApplicationSessionInitializer asi = getApplicationSessionInitializer();
          if (asi != null)
          {
              asi.initializeSession();
              Map<String, Object> sessionAttributes = asi.getSessionAttributes();
              if (sessionAttributes != null)
              {
                      setSessionAttributes(sessionAttributes);
              }
              propertyChangeSupport.firePropertyChange(SESSION_ATTRIBUTES, null, sessionAttributes);
          }
      }
docs: Initialize the session attributes.