ImmutableSortedMultiset.Builder<String> builder = ImmutableSortedMultiset.naturalOrder();
    assertThrows(IllegalArgumentException.class, () -> builder.addCopies("a", -2));
  }

  public void testBuilderSetCountHandlesNullsCorrectly() {
    ImmutableSortedMultiset.Builder<String> builder =
        new ImmutableSortedMultiset.Builder<>(Ordering.natural().nullsFirst());

    ImmutableSortedMultiset.Builder<String> builder = ImmutableSortedMultiset.naturalOrder();
    assertThrows(IllegalArgumentException.class, () -> builder.addCopies("a", -2));
  }

  public void testBuilderSetCountHandlesNullsCorrectly() {
    ImmutableSortedMultiset.Builder<String> builder =
        new ImmutableSortedMultiset.Builder<>(Ordering.natural().nullsFirst());

    try {
      builder.addCopies("a", -2);
      fail("expected IllegalArgumentException");
    } catch (IllegalArgumentException expected) {
    }
  }

  public void testBuilderSetCountHandlesNullsCorrectly() {
    ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
    try {
      builder.setCount(null, 2);
      fail("expected NullPointerException");