Entry<K, V> entry = getOnlyElement(map.entrySet());
        return ImmutableMap.of(entry.getKey(), entry.getValue());
      default:
        return new ImmutableEnumMap<>(map);
    }
  }

  private final transient EnumMap<K, V> delegate;

  private ImmutableEnumMap(EnumMap<K, V> delegate) {
    this.delegate = delegate;
    checkArgument(!delegate.isEmpty());
  }

  @Override
  UnmodifiableIterator<K> keyIterator() {

        Entry<K, V> entry = getOnlyElement(map.entrySet());
        return ImmutableMap.of(entry.getKey(), entry.getValue());
      default:
        return new ImmutableEnumMap<>(map);
    }
  }

  private final transient EnumMap<K, V> delegate;

  private ImmutableEnumMap(EnumMap<K, V> delegate) {
    this.delegate = delegate;
    checkArgument(!delegate.isEmpty());
  }

  @Override
  UnmodifiableIterator<K> keyIterator() {

        map.put(entry.getKey(), entry.getValue());
      }
      return Maps.immutableEnumMap(map);
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  public static Test suite() {
    TestSuite suite = new TestSuite();
    suite.addTest(
        MapTestSuiteBuilder.using(new ImmutableEnumMapGenerator())
            .named("Maps.immutableEnumMap")
            .withFeatures(CollectionSize.ANY, SERIALIZABLE, ALLOWS_NULL_QUERIES)

      Map<AnEnum, String> map = Maps.newHashMap();
      for (Entry<AnEnum, String> entry : entries) {
        checkNotNull(entry);
        map.put(entry.getKey(), entry.getValue());
      }
      return Maps.immutableEnumMap(map);
    }
  }

  public static class ImmutableMapCopyOfEnumMapGenerator extends TestEnumMapGenerator {
    @Override
    protected Map<AnEnum, String> create(Entry<AnEnum, String>[] entries) {

      } else {
        other.map.forEach(this::put);
        return this;
      }
    }

    ImmutableMap<K, V> toImmutableMap() {
      return (map == null) ? ImmutableMap.<K, V>of() : ImmutableEnumMap.asImmutable(map);
    }
  }

  @GwtIncompatible
  static <T extends @Nullable Object, K extends Comparable<? super K>, V>
      Collector<T, ?, ImmutableRangeMap<K, V>> toImmutableRangeMap(

   * @since 14.0
   */
  @GwtCompatible(serializable = true)
  public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
      Map<K, ? extends V> map) {
    if (map instanceof ImmutableEnumMap) {
      @SuppressWarnings("unchecked") // safe covariant cast
      ImmutableEnumMap<K, V> result = (ImmutableEnumMap<K, V>) map;
      return result;
    }

   * @since 14.0
   */
  @GwtCompatible(serializable = true)
  public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
      Map<K, ? extends V> map) {
    if (map instanceof ImmutableEnumMap) {
      @SuppressWarnings("unchecked") // safe covariant cast
      ImmutableEnumMap<K, V> result = (ImmutableEnumMap<K, V>) map;
      return result;
    }

  public void testCopyOfEnumMap() {
    EnumMap<AnEnum, String> map = new EnumMap<>(AnEnum.class);
    map.put(AnEnum.B, "foo");
    map.put(AnEnum.C, "bar");
    assertTrue(ImmutableMap.copyOf(map) instanceof ImmutableEnumMap);
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testViewSerialization() {
    Map<String, Integer> map = ImmutableMap.of("one", 1, "two", 2, "three", 3);

    EnumMap<K, V> copy = new EnumMap<>((EnumMap<K, ? extends V>) original);
    for (Entry<K, V> entry : copy.entrySet()) {
      checkEntryNotNull(entry.getKey(), entry.getValue());
    }
    return ImmutableEnumMap.asImmutable(copy);
  }

  static final Entry<?, ?>[] EMPTY_ENTRY_ARRAY = new Entry<?, ?>[0];

  abstract static class IteratorBasedImmutableMap<K, V> extends ImmutableMap<K, V> {