@VisibleForTesting
  static WildcardType subtypeOf(Type upperBound) {
    return new WildcardTypeImpl(new Type[0], new Type[] {upperBound});
  }

  /** Returns a new {@link WildcardType} with {@code lowerBound}. */
  @VisibleForTesting
  static WildcardType supertypeOf(Type lowerBound) {
    return new WildcardTypeImpl(new Type[] {lowerBound}, new Type[] {Object.class});
  }

  /**

    for (Type bound : type.getUpperBounds()) {
      if (!any(declared).isSubtypeOf(bound)) {
        upperBounds.add(canonicalizeWildcardsInType(bound));
      }
    }
    return new Types.WildcardTypeImpl(type.getLowerBounds(), upperBounds.toArray(new Type[0]));
  }

  private static ParameterizedType canonicalizeWildcardsInParameterizedType(
      ParameterizedType type) {