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});
  }

  /**
   * Returns a human-readable string representation of {@code type}.
   *

    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});
  }

  /**
   * Returns a human-readable string representation of {@code type}.
   *