/**
   * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> firstEntry();

  /**
   * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> lastEntry();

  /**

  /**
   * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> firstEntry();

  /**
   * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> lastEntry();

  /**

    Iterator<Entry<String, Collection<Integer>>> collectionIterator =
        multimap.asMap().entrySet().iterator();
    Entry<String, Collection<Integer>> entry = collectionIterator.next();
    assertThat(entry.getKey()).isEqualTo("foo");
    assertThat(entry.getValue()).containsExactly(5, 3).inOrder();
    entry = collectionIterator.next();
    assertThat(entry.getKey()).isEqualTo("bar");

      Multimap<K, V> multimap, ObjectOutputStream stream) throws IOException {
    stream.writeInt(multimap.asMap().size());
    for (Map.Entry<K, Collection<V>> entry : multimap.asMap().entrySet()) {
      stream.writeObject(entry.getKey());
      stream.writeInt(entry.getValue().size());
      for (V value : entry.getValue()) {
        stream.writeObject(value);
      }
    }
  }

  /**

  public @Nullable Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }
    return null;
  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {

import java.util.Map;
import java.util.Map.Entry;

/**
 * GWT emulation of {@link ImmutableEnumMap}. The type parameter is not bounded by {@code Enum<E>}
 * to avoid code-size bloat.
 *
 * @author Hayward Chan
 */
final class ImmutableEnumMap<K, V> extends ForwardingImmutableMap<K, V> {
  static <K, V> ImmutableMap<K, V> asImmutable(Map<K, V> map) {
    for (Entry<K, V> entry : checkNotNull(map).entrySet()) {

    } catch (UnsupportedOperationException e) {
      return;
    }
    if (map.size() < 2 || !supportsPut) {
      return;
    }
    Iterator<Entry<K, V>> iterator = map.entrySet().iterator();
    Entry<K, V> firstEntry = iterator.next();
    Entry<K, V> secondEntry = iterator.next();
    K key = secondEntry.getKey();
    SortedMap<K, V> subMap = map.tailMap(key);
    V value = getValueNotInPopulatedMap();

    } catch (UnsupportedOperationException e) {
      return;
    }
    if (map.size() < 2 || !supportsPut) {
      return;
    }
    Iterator<Entry<K, V>> iterator = map.entrySet().iterator();
    Entry<K, V> firstEntry = iterator.next();
    Entry<K, V> secondEntry = iterator.next();
    K key = secondEntry.getKey();
    SortedMap<K, V> subMap = map.tailMap(key);
    V value = getValueNotInPopulatedMap();

  public void testImmutableEntrySerialization() {
    Cell<String, Integer, Character> entry = immutableCell("foo", 1, 'a');
    SerializableTester.reserializeAndAssert(entry);
  }

  public void testImmutableEntryToString() {
    Cell<String, Integer, Character> entry = immutableCell("foo", 1, 'a');
    assertThat(entry.toString()).isEqualTo("(foo,1)=a");

  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutDuplicateValue() {
    List<Entry<K, V>> entries = copyToList(multimap().entries());

    for (Entry<K, V> entry : entries) {
      resetContainer();

      K k = entry.getKey();
      V v = entry.getValue();

      List<V> values = multimap().get(k);
      List<V> expectedValues = copyToList(values);