public void testCopyOfImmutableListMultimap() {
    Multimap<String, Integer> multimap = createMultimap();
    assertThat(ImmutableListMultimap.copyOf(multimap)).isSameInstanceAs(multimap);
  }

  public void testCopyOfNullKey() {
    ArrayListMultimap<@Nullable String, Integer> input = ArrayListMultimap.create();
    input.put(null, 1);
    assertThrows(
        NullPointerException.class,

  public void testCopyOfImmutableSetMultimap() {
    Multimap<String, Integer> multimap = createMultimap();
    assertThat(ImmutableSetMultimap.copyOf(multimap)).isSameInstanceAs(multimap);
  }

  public void testCopyOfNullKey() {
    HashMultimap<@Nullable String, Integer> input = HashMultimap.create();
    input.put(null, 1);
    assertThrows(
        NullPointerException.class,

  public void testCopyOfImmutableListMultimap() {
    Multimap<String, Integer> multimap = createMultimap();
    assertThat(ImmutableListMultimap.copyOf(multimap)).isSameInstanceAs(multimap);
  }

  public void testCopyOfNullKey() {
    ArrayListMultimap<@Nullable String, Integer> input = ArrayListMultimap.create();
    input.put(null, 1);
    assertThrows(
        NullPointerException.class,