/** GWT emulated version of {@link ImmutableCollection.Builder}. */
  public abstract static class Builder<E> {
    static final int DEFAULT_INITIAL_CAPACITY = 4;

    Builder() {}

    static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {
        throw new AssertionError("cannot store more than MAX_VALUE elements");
      }
      // careful of overflow!

     * current array, create a new array.
     */
    private void ensureRoomFor(int newElements) {
      @Nullable Object[] contents = this.contents;
      int newCapacity = expandedCapacity(contents.length, size + newElements);
      // expandedCapacity handles the overflow case
      if (newCapacity > contents.length || forceCopy) {
        this.contents = Arrays.copyOf(this.contents, newCapacity);
        forceCopy = false;
      }

           * sync with one another). We accommodate that by resizing as necessary.
           */
          toJoin = Arrays.copyOf(toJoin, expandedCapacity(toJoin.length, toJoin.length + 1));
        }
        toJoin[i++] = toString(part);
      }
      // We might not have seen the expected number of elements, as discussed above.
      if (i != toJoin.length) {

      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) {

      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) {

      this.size = 0;
    }

    private void ensureRoomFor(int newElements) {
      @Nullable Object[] contents = this.contents;
      int newCapacity = expandedCapacity(contents.length, size + newElements);
      // expandedCapacity handles the overflow case
      if (contents.length < newCapacity || copyOnWrite) {
        this.contents = Arrays.copyOf(contents, newCapacity);
        copyOnWrite = false;
      }

   *
   * @since 10.0
   */
  @DoNotMock
  public abstract static class Builder<E> {
    static final int DEFAULT_INITIAL_CAPACITY = 4;

    static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {
        throw new IllegalArgumentException("cannot store more than Integer.MAX_VALUE elements");
      } else if (minCapacity <= oldCapacity) {

         * sortAndDedup -- that is, at least c*n for some constant c > 0. Ensuring the buffer size
         * is at least expandedCapacity(n, n + 1) satisfies this property.
         */
        int newLength = ImmutableCollection.Builder.expandedCapacity(n, n + 1);
        if (newLength > elements.length) {
          elements = Arrays.copyOf(elements, newLength);
        }
      }

   */
  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);