code: @JSFProperty(tagExcluded = true)
      public String getViewId()
      {
          return (String) getStateHelper().get(PropertyKeys.viewId);
      }
docs: A unique identifier for the "template" from which this view was generated.
  <p>
  Typically this is the filesystem path to the template file, but the exact details are the responsibility of the
  current ViewHandler implementation.