ImmutableBiMap.of("one", 1, "two", 2, "three", 3),
            mapEntry("one", 1),
            mapEntry("two", 2),
            mapEntry("three", 3));
  }

  public void testToImmutableBiMap_exceptionOnDuplicateKey() {
    Collector<Entry<String, Integer>, ?, ImmutableBiMap<String, Integer>> collector =
        toImmutableBiMap(Entry::getKey, Entry::getValue);
    assertThrows(
        IllegalArgumentException.class,