}

  public void testClear() {
    table = create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    if (supportsRemove()) {
      table.clear();
      assertEquals(0, table.size());
      assertFalse(table.containsRow("foo"));
    } else {
      assertThrows(UnsupportedOperationException.class, () -> table.clear());
    }
  }

  public void testPut() {
    assertNull(table.put("foo", 1, cellValue('a')));

    /*
     * TODO(jlevy): Support only one of rowKey / columnKey being empty? If we
     * do, when columnKeys is empty but rowKeys isn't, rowKeyList() can contain
     * elements but rowKeySet() will be empty and containsRow() won't
     * acknowledge them.
     */
    rowKeyToIndex = Maps.indexMap(rowList);
    columnKeyToIndex = Maps.indexMap(columnList);

    @SuppressWarnings("unchecked")
    @Nullable

  /**
   * Returns {@code true} if the table contains a mapping with the specified row key.
   *
   * @param rowKey key of row to search for
   */
  boolean containsRow(@CompatibleWith("R") @CheckForNull Object rowKey);

  /**
   * Returns {@code true} if the table contains a mapping with the specified column.
   *
   * @param columnKey key of column to search for
   */

  /**
   * Returns {@code true} if the table contains a mapping with the specified row key.
   *
   * @param rowKey key of row to search for
   */
  boolean containsRow(@CompatibleWith("R") @CheckForNull Object rowKey);

  /**
   * Returns {@code true} if the table contains a mapping with the specified column.
   *
   * @param columnKey key of column to search for
   */

      synchronized (mutex) {
        return delegate().contains(rowKey, columnKey);
      }
    }

    @Override
    public boolean containsRow(@CheckForNull Object rowKey) {
      synchronized (mutex) {
        return delegate().containsRow(rowKey);
      }
    }

    @Override
    public boolean containsColumn(@CheckForNull Object columnKey) {
      synchronized (mutex) {

      synchronized (mutex) {
        return delegate().contains(rowKey, columnKey);
      }
    }

    @Override
    public boolean containsRow(@CheckForNull Object rowKey) {
      synchronized (mutex) {
        return delegate().containsRow(rowKey);
      }
    }

    @Override
    public boolean containsColumn(@CheckForNull Object columnKey) {
      synchronized (mutex) {