assertSame(Strength.STRONG, map.valueStrength());
    assertSame(map.keyStrength().defaultEquivalence(), map.keyEquivalence);
    assertSame(map.valueStrength().defaultEquivalence(), map.valueEquivalence());

    assertThat(map.entryHelper)
        .isInstanceOf(MapMakerInternalMap.StrongKeyStrongValueEntry.Helper.class);

    assertEquals(4, map.concurrencyLevel);

    // concurrency level

          Map<? extends K, ? extends V> left,
          Map<? extends K, ? extends V> right,
          Equivalence<? super @NonNull V> valueEquivalence) {
    Preconditions.checkNotNull(valueEquivalence);

    Map<K, V> onlyOnLeft = newLinkedHashMap();
    Map<K, V> onlyOnRight = new LinkedHashMap<>(right); // will whittle it down
    Map<K, V> onBoth = newLinkedHashMap();

          Map<? extends K, ? extends V> left,
          Map<? extends K, ? extends V> right,
          Equivalence<? super @NonNull V> valueEquivalence) {
    Preconditions.checkNotNull(valueEquivalence);

    Map<K, V> onlyOnLeft = newLinkedHashMap();
    Map<K, V> onlyOnRight = new LinkedHashMap<>(right); // will whittle it down
    Map<K, V> onBoth = newLinkedHashMap();