checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);
    keyStrength = checkNotNull(strength);
    if (strength != Strength.STRONG) {
      // STRONG could be used during deserialization.
      useCustomMap = true;
    }
    return this;
  }

  Strength getKeyStrength() {
    return MoreObjects.firstNonNull(keyStrength, Strength.STRONG);
  }

  /**

    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);
    keyStrength = checkNotNull(strength);
    if (strength != Strength.STRONG) {
      // STRONG could be used during deserialization.
      useCustomMap = true;
    }
    return this;
  }

  Strength getKeyStrength() {
    return MoreObjects.firstNonNull(keyStrength, Strength.STRONG);
  }

  /**

    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
      checkArgument(value == null, "key %s does not take values", key);
      checkArgument(spec.keyStrength == null, "%s was already set to %s", key, spec.keyStrength);
      spec.keyStrength = strength;
    }
  }

  /** Parse weakValues and softValues */
  private static final class ValueStrengthParser implements ValueParser {

    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
      checkArgument(value == null, "key %s does not take values", key);
      checkArgument(spec.keyStrength == null, "%s was already set to %s", key, spec.keyStrength);
      spec.keyStrength = strength;
    }
  }

  /** Parse weakValues and softValues */
  private static final class ValueStrengthParser implements ValueParser {

  public void testIdentityKeyEquality_weakKeys() {
    testIdentityKeyEquality(WEAK);
  }

  private void testIdentityKeyEquality(MapMakerInternalMap.Strength keyStrength) {

    ConcurrentMap<String, AtomicInteger> map =
        new MapMaker().setKeyStrength(keyStrength).keyEquivalence(Equivalence.identity()).makeMap();

    ConcurrentHashMultiset<String> multiset = ConcurrentHashMultiset.create(map);

    assertWithMessage("keyEquivalence")
        .that(actual.keyEquivalence)
        .isEqualTo(expected.keyEquivalence);
    assertWithMessage("keyStrength").that(actual.keyStrength).isEqualTo(expected.keyStrength);
    assertWithMessage("removalListener")
        .that(actual.removalListener)
        .isEqualTo(expected.removalListener);

  }

  private static void checkStrength(
      MapMakerInternalMap<Object, Object, ?, ?> map, Strength keyStrength, Strength valueStrength) {
    assertThat(map.keyStrength()).isEqualTo(keyStrength);
    assertThat(map.valueStrength()).isEqualTo(valueStrength);
    assertThat(map.keyEquivalence).isEqualTo(keyStrength.defaultEquivalence());
    assertThat(map.valueEquivalence()).isEqualTo(valueStrength.defaultEquivalence());
  }

  }

  private static void checkStrength(
      MapMakerInternalMap<Object, Object, ?, ?> map, Strength keyStrength, Strength valueStrength) {
    assertThat(map.keyStrength()).isEqualTo(keyStrength);
    assertThat(map.valueStrength()).isEqualTo(valueStrength);
    assertThat(map.keyEquivalence).isEqualTo(keyStrength.defaultEquivalence());
    assertThat(map.valueEquivalence()).isEqualTo(valueStrength.defaultEquivalence());
  }