*
   * MurmurHash3 was written by Austin Appleby, and is placed in the public domain. The author
   * hereby disclaims copyright to this source code.
   */
  static int smear(int hashCode) {
    return C2 * Integer.rotateLeft(hashCode * C1, 15);
  }

  private boolean checkFilter(int c) {
    return 1 == (1 & (filter >> c));
  }

  // This is all essentially copied from ImmutableSet, but we have to duplicate because

   *
   * MurmurHash3 was written by Austin Appleby, and is placed in the public domain. The author
   * hereby disclaims copyright to this source code.
   */
  static int smear(int hashCode) {
    return C2 * Integer.rotateLeft(hashCode * C1, 15);
  }

  private boolean checkFilter(int c) {
    return 1 == (1 & (filter >> c));
  }

  // This is all essentially copied from ImmutableSet, but we have to duplicate because

            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.
          requireNonNull(left);
          if (left.balanceFactor() < 0) {
            left = left.rotateLeft();
          }
          return rotateRight();
        default:
          recomputeHeight();