/**
   * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position.
   */
  void moveLastEntry(int dstIndex) {
    int srcIndex = size() - 1;
    if (dstIndex < srcIndex) {
      // move last entry to deleted spot
      keys[dstIndex] = keys[srcIndex];
      values[dstIndex] = values[srcIndex];
      keys[srcIndex] = null;
      values[srcIndex] = 0;

    if (delegate != null) {
      metadata =
          Ints.constrainToRange(size(), CompactHashing.DEFAULT_SIZE, CompactHashing.MAX_SIZE);
      delegate.clear(); // invalidate any iterators left over!
      table = null;
      size = 0;
    } else {
      Arrays.fill(requireKeys(), 0, size, null);
      Arrays.fill(requireValues(), 0, size, null);
      CompactHashing.tableClear(requireTable());

    @CheckForNull
    private Iterator<? extends Iterator<? extends T>> getTopMetaIterator() {
      while (topMetaIterator == null || !topMetaIterator.hasNext()) {
        if (metaIterators != null && !metaIterators.isEmpty()) {
          topMetaIterator = metaIterators.removeFirst();
        } else {
          return null;
        }
      }

   *
   * @throws NullPointerException if any key or value in {@code map} is null
   */
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableSortedMap<K, V> copyOfSorted(SortedMap<K, ? extends V> map) {
    Comparator<? super K> comparator = map.comparator();
    if (comparator == null) {
      // If map has a null comparator, the keys should have a natural ordering,

  }

  /*
   * All the ContiguousSet generators below manually reject nulls here. In principle, we'd like to
   * defer that to Range, since it's ContiguousSet.create() that's used to create the sets. However,
   * that gets messy here, and we already have null tests for Range.
   */

  /*
   * These generators also rely on consecutive integer inputs (not necessarily in order, but no

        prepareUnmodifiableTests(HashMultimap.<String, Integer>create(), false, null, null);
    SerializableTester.reserializeAndAssert(unmodifiable);
  }

  @GwtIncompatible // slow (~10s)
  public void testUnmodifiableTreeMultimap() {
    checkUnmodifiableMultimap(TreeMultimap.<String, Integer>create(), false, "null", 42);
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester

   * removal operations, and these are reflected in the underlying table.
   *
   * <p>It's acceptable for the underlying table to contain null keys, and even null values provided
   * that the function is capable of accepting null input. The transformed table might contain null
   * values, if the function sometimes gives a null result.
   *
   * <p>The returned table is not thread-safe or serializable, even if the underlying table is.
   *

    List<@Nullable String> list = newArrayList("a", null, "b", null, "a", null);
    assertEquals(2, Iterators.frequency(list.iterator(), "a"));
    assertEquals(1, Iterators.frequency(list.iterator(), "b"));
    assertEquals(0, Iterators.frequency(list.iterator(), "c"));
    assertEquals(0, Iterators.frequency(list.iterator(), 4.2));
    assertEquals(3, Iterators.frequency(list.iterator(), null));
  }

  @GwtIncompatible // slow (~4s)

    List<@Nullable String> list = newArrayList("a", null, "b", null, "a", null);
    assertEquals(2, Iterators.frequency(list.iterator(), "a"));
    assertEquals(1, Iterators.frequency(list.iterator(), "b"));
    assertEquals(0, Iterators.frequency(list.iterator(), "c"));
    assertEquals(0, Iterators.frequency(list.iterator(), 4.2));
    assertEquals(3, Iterators.frequency(list.iterator(), null));
  }

  @GwtIncompatible // slow (~4s)

                  }
                })
            .named("TreeMultimap nullsFirst")
            .withFeatures(
                MapFeature.ALLOWS_NULL_KEYS,
                MapFeature.ALLOWS_NULL_VALUES,
                MapFeature.ALLOWS_ANY_NULL_QUERIES,
                MapFeature.GENERAL_PURPOSE,
                MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
                CollectionFeature.SUPPORTS_ITERATOR_REMOVE,