Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a", "b", "a")), multiset);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(
        NullPointerException.class, () -> ImmutableMultiset.copyOf((Collection<String>) c));
  }

    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a", "b", "a")), multiset);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(
        NullPointerException.class, () -> ImmutableMultiset.copyOf((Collection<String>) c));
  }

    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a", "b", "a")), multiset);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<String> c = MinimalCollection.of("a", null, "b");
    assertThrows(NullPointerException.class, () -> ImmutableSortedMultiset.copyOf(c));
  }

  public void testCopyOf_multiset_empty() {

    Set<String> set = copyOf(c);
    assertEquals(2, set.size());
    assertTrue(set.contains("a"));
    assertTrue(set.contains("b"));
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(NullPointerException.class, () -> copyOf((Collection<String>) c));
  }

  enum TestEnum {
    A,

    List<String> mutableList = asList("a", "b");
    list = ImmutableList.copyOf(mutableList);
    mutableList.set(0, "c");
    assertEquals(asList("a", "b"), list);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(NullPointerException.class, () -> ImmutableList.copyOf((Collection<String>) c));
  }

    List<String> mutableList = asList("a", "b");
    list = ImmutableList.copyOf(mutableList);
    mutableList.set(0, "c");
    assertEquals(asList("a", "b"), list);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(NullPointerException.class, () -> ImmutableList.copyOf((Collection<String>) c));
  }