// Mutate the value
    holder.string = "bar";

    // Make sure it uses the original value.
    assertEquals(ImmutableTable.of('K', 42, "foo"), builder.buildOrThrow());
  }

  public void testBuilder_noDuplicates() {
    ImmutableTable.Builder<Character, Integer, String> builder =
        new ImmutableTable.Builder<Character, Integer, String>()
            .put('a', 1, "foo")
            .put('a', 1, "bar");