IllegalArgumentException expected =
        assertThrows(IllegalArgumentException.class, () -> ImmutableBiMap.of("one", 1, "one", 1));
    assertThat(expected).hasMessageThat().contains("one");
  }

  public void testOfEntries() {
    assertMapEquals(ImmutableBiMap.ofEntries(entry("one", 1), entry("two", 2)), "one", 1, "two", 2);
  }

  public void testOfEntriesNull() {
    Entry<@Nullable Integer, Integer> nullKey = entry(null, 23);