// deal with empty-map optimization.
    map1.put(0, null);

    int initialBuckets = bucketsOf(map1);

    for (int i = 1; i < size; i++) {
      map1.put(i, null);
    }
    assertWithMessage("table size after adding %s elements", size)
        .that(bucketsOf(map1))
        .isEqualTo(initialBuckets);

    /*