checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

  /**
   * Sets a custom {@code Equivalence} strategy for comparing values.
   *

   */
  private MapMakerInternalMap(MapMaker builder, InternalEntryHelper<K, V, E, S> entryHelper) {
    concurrencyLevel = min(builder.getConcurrencyLevel(), MAX_SEGMENTS);

    keyEquivalence = builder.getKeyEquivalence();
    this.entryHelper = entryHelper;

    int initialCapacity = min(builder.getInitialCapacity(), MAXIMUM_CAPACITY);

    // Find power-of-two sizes best matching arguments. Constraints: