assertEquals(c, sortedMultiset.tailMultiset(b.getElement(), CLOSED).firstEntry());
    assertEquals(c, sortedMultiset.tailMultiset(c.getElement(), CLOSED).firstEntry());
  }

  @CollectionSize.Require(SEVERAL)
  public void testHigher() {
    resetWithHole();
    assertEquals(c, sortedMultiset.tailMultiset(a.getElement(), OPEN).firstEntry());

    assertEquals(c, sortedMultiset.tailMultiset(b.getElement(), CLOSED).firstEntry());
    assertEquals(c, sortedMultiset.tailMultiset(c.getElement(), CLOSED).firstEntry());
  }

  @CollectionSize.Require(SEVERAL)
  public void testHigher() {
    resetWithHole();
    assertEquals(c, sortedMultiset.tailMultiset(a.getElement(), OPEN).firstEntry());

    super.resetMap(entries);
    navigableMap = (NavigableMap<K, V>) getMap();
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapFirst() {
    assertNull(navigableMap.firstEntry());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testEmptyMapPollFirst() {
    assertNull(navigableMap.pollFirstEntry());
  }

  @CollectionSize.Require(ZERO)

      result.descendingMultiset = this;
      return descendingMultiset = result;
    }
    return result;
  }

  @Override
  @CheckForNull
  public Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  @Override
  @CheckForNull
  public Entry<E> lastEntry() {
    return delegate().lastEntry();
  }

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {

  }

  @Override
  public Range<K> span() {
    Entry<Cut<K>, RangeMapEntry<K, V>> firstEntry = entriesByLowerBound.firstEntry();
    Entry<Cut<K>, RangeMapEntry<K, V>> lastEntry = entriesByLowerBound.lastEntry();
    // Either both are null or neither is, but we check both to satisfy the nullness checker.
    if (firstEntry == null || lastEntry == null) {
      throw new NoSuchElementException();
    }
    return Range.create(

              });
          // requireNonNull is safe because the first `size` elements have been filled in.
          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
          K prevKey = firstEntry.getKey();
          keys[0] = prevKey;
          values[0] = firstEntry.getValue();
          checkEntryNotNull(keys[0], values[0]);
          for (int i = 1; i < size; i++) {

    valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();
    entries.remove(firstEntry);
    assertFalse(underlying.containsKey("f"));

    Iterator<Entry<String, String>> entryIterator = entries.iterator();
    entryIterator.next();
    entryIterator.remove();

  }

  @Override
  public Range<K> span() {
    Entry<Cut<K>, RangeMapEntry<K, V>> firstEntry = entriesByLowerBound.firstEntry();
    Entry<Cut<K>, RangeMapEntry<K, V>> lastEntry = entriesByLowerBound.lastEntry();
    // Either both are null or neither is, but we check both to satisfy the nullness checker.
    if (firstEntry == null || lastEntry == null) {
      throw new NoSuchElementException();
    }
    return Range.create(

    valueIterator.next();
    valueIterator.remove();
    assertFalse(underlying.containsKey("e"));

    Set<Entry<String, String>> entries = map.entrySet();
    Entry<String, String> firstEntry = entries.iterator().next();
    entries.remove(firstEntry);
    assertFalse(underlying.containsKey("f"));

    Iterator<Entry<String, String>> entryIterator = entries.iterator();
    entryIterator.next();
    entryIterator.remove();

              });
          // requireNonNull is safe because the first `size` elements have been filled in.
          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
          K prevKey = firstEntry.getKey();
          keys[0] = prevKey;
          values[0] = firstEntry.getValue();
          checkEntryNotNull(keys[0], values[0]);
          for (int i = 1; i < size; i++) {