}

  /**
   * Returns, as an immutable list, the row keys provided when the table was constructed, including
   * those that are mapped to null values only.
   */
  public ImmutableList<R> rowKeyList() {
    return rowList;
  }

  /**
   * Returns, as an immutable list, the column keys provided when the table was constructed,
   * including those that are mapped to null values only.
   */

    return ImmutableList.copyOf(elements);
  }

  /**
   * Utility method to verify that the given LinkedHashSet is equal to and hashes identically to a
   * set constructed with the elements in the given collection. Also verifies that the ordering in
   * the set is the same as the ordering of the given contents.
   */
  private static <E> void verifyLinkedHashSetContents(

   *
   * <p><i>Performance notes:</i> while the cartesian product of lists of size {@code m, n, p} is a
   * list of size {@code m x n x p}, its actual memory consumption is much smaller. When the
   * cartesian product is constructed, the input lists are merely copied. Only as the resulting list
   * is iterated are the individual lists created, and these are not retained after iteration.
   *

    Builder(int expectedKeys) {
      if (expectedKeys > 0) {
        builderMap = Platform.preservesInsertionOrderOnPutsMapWithExpectedSize(expectedKeys);
      }
      // otherwise, leave it null to be constructed lazily
    }

    Map<K, ImmutableCollection.Builder<V>> ensureBuilderMapNonNull() {
      Map<K, ImmutableCollection.Builder<V>> result = builderMap;
      if (result == null) {