if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }

    // Unfortunately this is pasted from ImmutableCollection.Builder.
    private static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {

      if (newCount > array.length) {
        array = Arrays.copyOf(array, expandedCapacity(array.length, newCount));
      }
    }

    // Unfortunately this is pasted from ImmutableCollection.Builder.
    private static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {

   */
  private void ensureCapacity(int minCapacity) {
    if (nextInBucketKToV.length < minCapacity) {
      int oldCapacity = nextInBucketKToV.length;
      int newCapacity = ImmutableCollection.Builder.expandedCapacity(oldCapacity, minCapacity);

      keys = Arrays.copyOf(keys, newCapacity);
      values = Arrays.copyOf(values, newCapacity);
      nextInBucketKToV = expandAndFillWithAbsent(nextInBucketKToV, newCapacity);