code: @Deprecated
    public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1) {
      throw new UnsupportedOperationException();
    }
docs: 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
  ImmutableSortedMap#of(Comparable, Object)}.</b>