setListAttributes() {
    this.config.listAttributes.forEach((attribute) => {
      if (this.hasOwnProperty(attribute) && this[attribute]) {
        this[attribute] = this[attribute].split(',').map((item) => {
          return item.trim();
        });
      }
    });
  }
Set list attributes.
@method
@description
Sets front matter attributes that are specified as list attributes to
an array by splitting the string by commas.