* This class has a modern API. It avoids punitive checked exceptions: [toHttpUrl] throws
 * [IllegalArgumentException] on invalid input or [toHttpUrlOrNull] returns null if the input is an
 * invalid URL. You can even be explicit about whether each component has been encoded already.
 *
 * [idna]: http://www.unicode.org/reports/tr46/#ToASCII
 */
class HttpUrl private constructor(
  /** Either "http" or "https". */