* identical. Otherwise, returns true as long as {@code actualType} is present.
   */
  private static boolean matchesType(
      Optional<PublicSuffixType> desiredType, Optional<PublicSuffixType> actualType) {
    return desiredType.isPresent() ? desiredType.equals(actualType) : actualType.isPresent();
  }

  /** Returns the domain name, normalized to all lower case. */
  @Override