public void testBuilder_orderEntriesByValueFails() {
    ImmutableSortedMap.Builder<String, Integer> builder = ImmutableSortedMap.naturalOrder();
    assertThrows(
        UnsupportedOperationException.class, () -> builder.orderEntriesByValue(Ordering.natural()));
  }

  public void testBuilder_withImmutableEntry() {
    ImmutableSortedMap<String, Integer> map =