assertThrows(
            NullPointerException.class,
            () -> ImmutableSortedMap.copyOf((Map<Integer, Integer>) source));
      }
    }
  }

  public void testNullValuesInCopyOfEntries() {
    for (int i = 1; i <= 10; i++) {
      for (int j = 0; j < i; j++) {
        Map<Integer, @Nullable Integer> source = new TreeMap<>();
        for (int k = 0; k < i; k++) {
          source.put(k, k);