assertThrows(IllegalArgumentException.class, () -> maker.initialCapacity(-1));
  }

  // TODO(cpovirk): enable when ready (apparently after a change to our GWT emulation)
  public void xtestInitialCapacity_setTwice() {
    MapMaker maker = new MapMaker().initialCapacity(16);
    try {
      // even to the same value is not allowed
      maker.initialCapacity(16);
      fail();