return ImmutableMap.<C, Map<R, V>>copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.
    ImmutableMap<R, ImmutableMap<C, V>> rowMap = this.rowMap;
    return ImmutableMap.<R, Map<C, V>>copyOf(rowMap);
  }

  @Override
  public int size() {
    return cellRowIndices.length;
  }

  @Override

      return super.put(key, value);
    }
  }

  // rowKeySet() and rowMap() are defined here so they appear in the Javadoc.

  @Override
  public SortedSet<R> rowKeySet() {
    return super.rowKeySet();
  }

  @Override
  public SortedMap<R, Map<C, V>> rowMap() {
    return super.rowMap();
  }

  /** Overridden column iterator to return columns values in globally sorted order. */

  }

  @LazyInit @CheckForNull private transient RowMap rowMap;

  @Override
  public Map<R, Map<C, @Nullable V>> rowMap() {
    RowMap map = rowMap;
    return (map == null) ? rowMap = new RowMap() : map;
  }

  @WeakOuter
  private class RowMap extends ArrayMap<R, Map<C, @Nullable V>> {
    private RowMap() {
      super(rowKeyToIndex);
    }

    @Override

  }

  @Override
  public Collection<E> getSampleElements(int howMany) {
    SampleElements<E> samples = samples();
    List<E> allSampleElements =
        Arrays.asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
    return new ArrayList<>(allSampleElements.subList(0, howMany));
  }

  @Override
  public CollectionSize getCollectionSize() {
    return collectionSize;

    public Set<R> rowKeySet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowKeySet();
    }

    @Override
    public Map<R, Map<C, V>> rowMap() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.rowMap();
    }

    private static final long serialVersionUID = 0;
  }

  @Override
  protected Table<String, Integer, Character> create(@Nullable Object... data) {

        // success
      }
    }
  }

  public final void testConsistentToString() {
    for (ImmutableTable<Character, Integer, String> testInstance : getTestInstances()) {
      assertEquals(testInstance.rowMap().toString(), testInstance.toString());
    }
  }

  public final void testConsistentHashCode() {
    for (ImmutableTable<Character, Integer, String> testInstance : getTestInstances()) {

  }

  public void testRowKeySet() {
    assertEquals(ImmutableSet.of(), INSTANCE.rowKeySet());
  }

  public void testRowMap() {
    assertEquals(ImmutableMap.of(), INSTANCE.rowMap());
  }

  public void testValues() {
    assertTrue(INSTANCE.values().isEmpty());
  }

  }

  public void testRowKeySet() {
    assertEquals(ImmutableSet.of(), INSTANCE.rowKeySet());
  }

  public void testRowMap() {
    assertEquals(ImmutableMap.of(), INSTANCE.rowMap());
  }

  public void testValues() {
    assertTrue(INSTANCE.values().isEmpty());
  }

    TreeBasedTable<String, Integer, Character> table = makeTable();
    populateTable(table);
    return table.rowMap().headMap("x");
  }

  @Override
  protected Map<String, Map<Integer, Character>> makeEmptyMap() {
    return makeTable().rowMap().headMap("x");
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "z";
  }

  }

  public void testRowKeySet() {
    assertEquals(ImmutableSet.of('a'), testTable.rowKeySet());
  }

  public void testRowMap() {
    assertEquals(ImmutableMap.of('a', ImmutableMap.of(1, "blah")), testTable.rowMap());
  }

  public void testEqualsObject() {
    new EqualsTester()
        .addEqualityGroup(testTable, HashBasedTable.create(testTable))
        .addEqualityGroup(ImmutableTable.of(), HashBasedTable.create())