@SuppressWarnings("unchecked")
  public static <K, V> ImmutableListMultimap<K, V> of() {
    return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
  }

  /** Returns an immutable multimap containing a single entry. */
  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
    builder.put(k1, v1);

  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableListMultimap<K, V> of() {
    return (ImmutableListMultimap<K, V>) EmptyImmutableListMultimap.INSTANCE;
  }

  /** Returns an immutable multimap containing a single entry. */
  public static <K, V> ImmutableListMultimap<K, V> of(K k1, V v1) {
    ImmutableListMultimap.Builder<K, V> builder = ImmutableListMultimap.builder();
    builder.put(k1, v1);

    assertEquals(ImmutableListMultimap.of(1, "one"), ImmutableListMultimap.of("one", 1).inverse());
    assertEquals(
        ImmutableListMultimap.of(1, "one", 2, "two"),
        ImmutableListMultimap.of("one", 1, "two", 2).inverse());
    assertEquals(
        ImmutableListMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o').inverse(),
        ImmutableListMultimap.of('o', "of", 'f', "of", 't', "to", 'o', "to"));

    assertEquals(ImmutableListMultimap.of(1, "one"), ImmutableListMultimap.of("one", 1).inverse());
    assertEquals(
        ImmutableListMultimap.of(1, "one", 2, "two"),
        ImmutableListMultimap.of("one", 1, "two", 2).inverse());
    assertEquals(
        ImmutableListMultimap.of("of", 'o', "of", 'f', "to", 't', "to", 'o').inverse(),
        ImmutableListMultimap.of('o', "of", 'f', "of", 't', "to", 'o', "to"));

        ImmutableListMultimap.Builder::combine,
        ImmutableListMultimap.Builder::build);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap(
          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
    checkNotNull(keyFunction);

        setMultimap,
        setMultimapCopy);

    ImmutableListMultimap<String, String> listMultimap = ImmutableListMultimap.of("k1", "v1");
    ImmutableMultimap<String, String> listMultimapCopy = ImmutableMultimap.copyOf(listMultimap);
    assertSame(
        "copyOf(ImmutableListMultimap) should not create a new instance",
        listMultimap,
        listMultimapCopy);
  }

                return wrap((ListMultimap<?, ?>) delegate);
              }
            });
  }

  public void testEquals() {
    ListMultimap<Integer, String> map1 = ImmutableListMultimap.of(1, "one");
    ListMultimap<Integer, String> map2 = ImmutableListMultimap.of(2, "two");
    new EqualsTester()
        .addEqualityGroup(map1, wrap(map1), wrap(map1))
        .addEqualityGroup(map2, wrap(map2))
        .testEquals();
  }

                return wrap((ListMultimap<?, ?>) delegate);
              }
            });
  }

  public void testEquals() {
    ListMultimap<Integer, String> map1 = ImmutableListMultimap.of(1, "one");
    ListMultimap<Integer, String> map2 = ImmutableListMultimap.of(2, "two");
    new EqualsTester()
        .addEqualityGroup(map1, wrap(map1), wrap(map1))
        .addEqualityGroup(map2, wrap(map2))
        .testEquals();
  }

import com.google.common.annotations.GwtCompatible;
import java.util.Collection;

/**
 * Implementation of {@link ImmutableListMultimap} with no entries.
 *
 * @author Jared Levy
 */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
class EmptyImmutableListMultimap extends ImmutableListMultimap<Object, Object> {
  static final EmptyImmutableListMultimap INSTANCE = new EmptyImmutableListMultimap();

  }

  private static final ImmutableListMultimap<String, String> PARAMETERS =
      ImmutableListMultimap.of("a", "1", "a", "2", "b", "3");

  public void testGetParameters() {
    assertEquals(ImmutableListMultimap.of(), MediaType.parse("text/plain").parameters());
    assertEquals(
        ImmutableListMultimap.of("charset", "utf-8"),