builder.put("key", "value");
    assertThat(builder.build().entries()).containsExactly(Maps.immutableEntry("key", "value"));
  }

  static class HashHostileComparable implements Comparable<HashHostileComparable> {
    final String string;

    public HashHostileComparable(String string) {
      this.string = string;
    }

    @Override
    public int hashCode() {
      throw new UnsupportedOperationException();