* 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 ((filter >> c) & 1) == 1;
  }

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