ImmutableMap::copyOf);
  }

  @SuppressWarnings("unchecked") // An empty map works for all types.
  public static <K, V> ImmutableMap<K, V> of() {
    return (ImmutableMap<K, V>) RegularImmutableMap.EMPTY;
  }

  public static <K, V> ImmutableMap<K, V> of(K k1, V v1) {
    return ImmutableBiMap.of(k1, v1);
  }

  public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2) {

   * @throws NullPointerException if any key or value in {@code map} is null
   */
  public static <K, V> ImmutableMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
    if ((map instanceof ImmutableMap) && !(map instanceof SortedMap)) {
      @SuppressWarnings("unchecked") // safe since map is not writable
      ImmutableMap<K, V> kvMap = (ImmutableMap<K, V>) map;
      if (!kvMap.isPartialView()) {
        return kvMap;
      }
    }

     * java.util.LinkedHashMap LinkedHashMap} and {@link ImmutableMap#copyOf(Map)} rather than
     * {@code ImmutableMap.Builder}.
     *
     * @since 31.1
     */
    public ImmutableMap<K, V> buildKeepingLast() {
      return build(false);
    }

    @VisibleForTesting // only for testing JDK backed implementation
    ImmutableMap<K, V> buildJdkBacked() {
      checkState(

    new EqualsTester()
        .addEqualityGroup(
            ImmutableMap.of(),
            ImmutableMap.builder().buildOrThrow(),
            ImmutableMap.ofEntries(),
            map())
        .addEqualityGroup(
            ImmutableMap.of(1, 1),
            ImmutableMap.builder().put(1, 1).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1)),
            map(1, 1))
        .addEqualityGroup(

    }
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    ImmutableMap<C, ImmutableMap<R, V>> columnMap = this.columnMap;
    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.
    ImmutableMap<R, ImmutableMap<C, V>> rowMap = this.rowMap;

    new EqualsTester()
        .addEqualityGroup(
            ImmutableMap.of(),
            ImmutableMap.builder().buildOrThrow(),
            ImmutableMap.ofEntries(),
            map())
        .addEqualityGroup(
            ImmutableMap.of(1, 1),
            ImmutableMap.builder().put(1, 1).buildOrThrow(),
            ImmutableMap.ofEntries(entry(1, 1)),
            map(1, 1))
        .addEqualityGroup(

    }
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    ImmutableMap<C, ImmutableMap<R, V>> columnMap = this.columnMap;
    return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.
    ImmutableMap<R, ImmutableMap<C, V>> rowMap = this.rowMap;

    assertEquals(ImmutableMap.of(1, 'a', 3, 'c'), row);
    assertEquals(ImmutableMap.of(3, 'c'), subRow);
    table.remove("foo", 3);
    assertEquals(ImmutableMap.of(1, 'a'), row);
    assertEquals(ImmutableMap.of(), subRow);
    table.remove("foo", 1);
    assertEquals(ImmutableMap.of(), row);
    assertEquals(ImmutableMap.of(), subRow);
    table.put("foo", 2, 'b');

    new EqualsTester()
        .addEqualityGroup(
            EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CANADA)),
            EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CANADA)))
        .addEqualityGroup(EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CHILE)))
        .addEqualityGroup(EnumBiMap.create(ImmutableMap.of(Currency.FRANC, Country.CANADA)))
        .testEquals();
  }

    new EqualsTester()
        .addEqualityGroup(
            EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CANADA)),
            EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CANADA)))
        .addEqualityGroup(EnumBiMap.create(ImmutableMap.of(Currency.DOLLAR, Country.CHILE)))
        .addEqualityGroup(EnumBiMap.create(ImmutableMap.of(Currency.FRANC, Country.CANADA)))
        .testEquals();
  }