docs: private Map<String, Object> _getActiveFlashMap()
      {
          FacesContext facesContext = FacesContext.getCurrentInstance();
          if (PhaseId.RENDER_RESPONSE.equals(facesContext.getCurrentPhaseId()) 
                  || !facesContext.isPostback())
          {
              return _getRenderFlashMap(facesContext);
          }
          else
          {
              return _getExecuteFlashMap(facesContext);
          }
      }