_findAllTagValues(names) {
    const tags = this._findAll(names);
    if (!tags) return null;

    const results = [];
    for (const tag of tags) {
      results.push(tag.tagValue);
    }

    return results;
  }
find all tag values.
@param {string[]} names - tag names.
@returns {*[]|null} found values.
@private