guava/src/com/google/common/reflect/Types.java
@VisibleForTesting
  static WildcardType supertypeOf(Type lowerBound) {
    return new WildcardTypeImpl(new Type[] {lowerBound}, new Type[] {Object.class});
  }
@VisibleForTesting
  static WildcardType supertypeOf(Type lowerBound) {
    return new WildcardTypeImpl(new Type[] {lowerBound}, new Type[] {Object.class});
  }
Returns a new {@link WildcardType} with {@code lowerBound}.