assertEquals(c, navigableMap.pollLastEntry());
    assertEquals(entries.subList(0, entries.size() - 1), copyToList(navigableMap.entrySet()));
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollLastUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> navigableMap.pollLastEntry());
  }

  @CollectionSize.Require(SEVERAL)

  public void testPollLast() {
    assertEquals(c, sortedMultiset.pollLastEntry());
    assertEquals(asList(a, b), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollLastUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> sortedMultiset.pollLastEntry());
  }

  @CollectionSize.Require(SEVERAL)

  public void testPollLast() {
    assertEquals(c, sortedMultiset.pollLastEntry());
    assertEquals(asList(a, b), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollLastUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> sortedMultiset.pollLastEntry());
  }

  @CollectionSize.Require(SEVERAL)

  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {

      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {
      return standardPollFirstEntry();
    }

    @Override
    public Entry<E> pollLastEntry() {
      return standardPollLastEntry();
    }

    @Override
    public SortedMultiset<E> subMultiset(
        E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {

      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {
      return standardPollFirstEntry();
    }

    @Override
    public Entry<E> pollLastEntry() {
      return standardPollLastEntry();
    }

    @Override
    public SortedMultiset<E> subMultiset(
        E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {

    public Entry<K, V2> pollFirstEntry() {
      return transformEntry(fromMap().pollFirstEntry());
    }

    @Override
    @CheckForNull
    public Entry<K, V2> pollLastEntry() {
      return transformEntry(fromMap().pollLastEntry());
    }

    @Override
    public NavigableMap<K, V2> subMap(
        @ParametricNullness K fromKey,
        boolean fromInclusive,

    public Entry<K, V2> pollFirstEntry() {
      return transformEntry(fromMap().pollFirstEntry());
    }

    @Override
    @CheckForNull
    public Entry<K, V2> pollLastEntry() {
      return transformEntry(fromMap().pollLastEntry());
    }

    @Override
    public NavigableMap<K, V2> subMap(
        @ParametricNullness K fromKey,
        boolean fromInclusive,

        return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
      }
    }

    @Override
    @CheckForNull
    public Map.Entry<K, V> pollLastEntry() {
      synchronized (mutex) {
        return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
      }
    }

    @Override
    public NavigableMap<K, V> subMap(

        return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
      }
    }

    @Override
    @CheckForNull
    public Map.Entry<K, V> pollLastEntry() {
      synchronized (mutex) {
        return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
      }
    }

    @Override
    public NavigableMap<K, V> subMap(