throw new UnsupportedOperationException();
  }

  /**
   * Not supported. <b>You are attempting to create a map that may contain a non-{@code Comparable}
   * key.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this dummy
   * version.
   *
   * @throws UnsupportedOperationException always
   * @deprecated <b>Pass a key of type {@code Comparable} to use {@link

    throw new UnsupportedOperationException();
  }

  /**
   * Not supported. <b>You are attempting to create a set that may contain a non-{@code Comparable}
   * element.</b> Proper calls will resolve to the version in {@code ImmutableSortedSet}, not this
   * dummy version.
   *
   * @throws UnsupportedOperationException always

      // If ApiProxy doesn't exist, we're not on AppEngine at all.
      return false;
    } catch (InvocationTargetException e) {
      // If ApiProxy throws an exception, we're not in a proper AppEngine environment.
      return false;
    } catch (IllegalAccessException e) {
      // If the method isn't accessible, we're not on a supported version of AppEngine;
      return false;

    throw new UnsupportedOperationException();
  }

  /**
   * Not supported. <b>You are attempting to create a multiset that may contain a non-{@code
   * Comparable} element.</b> Proper calls will resolve to the version in {@code
   * ImmutableSortedMultiset}, not this dummy version.
   *
   * @throws UnsupportedOperationException always

  /**
   * The HTTP <a href="https://goo.gl/VKpXxa">{@code X-Download-Options}</a> header field name.
   *
   * <p>When the new X-Download-Options header is present with the value {@code noopen}, the user is
   * prevented from opening a file download directly; instead, they must first save the file
   * locally.
   *
   * @since 24.1
   */