getDisplayName_(type) {
    for (let i = 0; i < this.types_.length; i++) {
      const typeNames = this.types_[i];
      if (type === typeNames[1]) {
        return typeNames[0];
      }
    }
    return '';
  }
Get the display name for the given type.
@param {string} type The type to get the display name for.
@returns {string} The display name for the type.
@private