docs: function getRichItemNames(textStyleModel) {
      // Use object to remove duplicated names.
      var richItemNameMap;
      while (textStyleModel && textStyleModel !== textStyleModel.ecModel) {
          var rich = (textStyleModel.option || EMPTY_OBJ).rich;
          if (rich) {
              richItemNameMap = richItemNameMap || {};
              for (var name in rich) {
                  if (rich.hasOwnProperty(name)) {
                      richItemNameMap[name] = 1;
                  }
              }
          }
          textStyleModel = textStyleModel.parentModel;
      }
      return richItemNameMap;
  }