* @throws NullPointerException if any key or value in {@code map} is null
   */
  public static <K, V> ImmutableBiMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
    if (map instanceof ImmutableBiMap) {
      @SuppressWarnings("unchecked") // safe since map is not writable
      ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
      // TODO(lowasser): if we need to make a copy of a BiMap because the

 */
public class HttpHeadersTest extends TestCase {

  public void testConstantNameMatchesString() throws Exception {
    // Special case some of the weird HTTP Header names...
    ImmutableBiMap<String, String> specialCases =
        ImmutableBiMap.<String, String>builder()
            .put("CDN_LOOP", "CDN-Loop")
            .put("ETAG", "ETag")
            .put("SOURCE_MAP", "SourceMap")

          .put(SortedMultiset.class, ImmutableSortedMultiset.of())
          .put(ImmutableSortedMultiset.class, ImmutableSortedMultiset.of())
          .put(BiMap.class, ImmutableBiMap.of())
          .put(ImmutableBiMap.class, ImmutableBiMap.of())
          .put(Table.class, ImmutableTable.of())
          .put(ImmutableTable.class, ImmutableTable.of())

          .put(SortedMultiset.class, ImmutableSortedMultiset.of())
          .put(ImmutableSortedMultiset.class, ImmutableSortedMultiset.of())
          .put(BiMap.class, ImmutableBiMap.of())
          .put(ImmutableBiMap.class, ImmutableBiMap.of())
          .put(Table.class, ImmutableTable.of())
          .put(ImmutableTable.class, ImmutableTable.of())

  public void testAsConverter_toString() {
    ImmutableBiMap<String, Integer> biMap =
        ImmutableBiMap.of(
            "one", 1,
            "two", 2);
    Converter<String, Integer> converter = Maps.asConverter(biMap);
    assertEquals("Maps.asConverter({one=1, two=2})", converter.toString());
  }

  public void testAsConverter_serialization() {
    ImmutableBiMap<String, Integer> biMap =
        ImmutableBiMap.of(

  public void testAsConverter_toString() {
    ImmutableBiMap<String, Integer> biMap =
        ImmutableBiMap.of(
            "one", 1,
            "two", 2);
    Converter<String, Integer> converter = Maps.asConverter(biMap);
    assertEquals("Maps.asConverter({one=1, two=2})", converter.toString());
  }

  public void testAsConverter_serialization() {
    ImmutableBiMap<String, Integer> biMap =
        ImmutableBiMap.of(

    HashBiMap<K, V> bimap = HashBiMap.create();
    bimap.put(key, value);
    return bimap;
  }

  @Generates
  static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
    return ImmutableBiMap.of(key, value);
  }

  @Generates
  static <R, C, V> Table<R, C, V> generateTable(R row, C column, V value) {
    return generateHashBasedTable(row, column, value);
  }

    HashBiMap<K, V> bimap = HashBiMap.create();
    bimap.put(key, value);
    return bimap;
  }

  @Generates
  static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
    return ImmutableBiMap.of(key, value);
  }

  @Generates
  static <R, C, V> Table<R, C, V> generateTable(R row, C column, V value) {
    return generateHashBasedTable(row, column, value);
  }

  }

  static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> biMap(
      BiMap<K, V> bimap, @CheckForNull Object mutex) {
    if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
      return bimap;
    }
    return new SynchronizedBiMap<>(bimap, mutex, null);
  }

  static final class SynchronizedBiMap<K extends @Nullable Object, V extends @Nullable Object>