Table<Character, Integer, String> table = builder.buildOrThrow();
    assertThat(table).isInstanceOf(SparseImmutableTable.class);
    validateReserialization(table);
  }

  public void testSparseSerialization_rowOrder() {
    ImmutableTable.Builder<Character, Integer, String> builder = ImmutableTable.builder();
    builder.orderRowsBy(Ordering.<Character>natural());
    builder.put('b', 2, "foo");