setCssClass(t, s) {
    t.split(",").forEach((n) => {
      let o = this.getState(n);
      if (o === void 0) {
        const c = n.trim();
        this.addState(c), o = this.getState(c);
      }
      o.classes.push(s);
    });
  }
Add a (style) class or css class to a state with the given id.
If the state isn't already in the list of known states, add it.
Might be called by parser when a style class or CSS class should be applied to a state

@param {string | string[]} itemIds The id or a list of ids of the item(s) to apply the css class to
@param {string} cssClassName CSS class name