public static WildcardType supertypeOf(Type bound) {
        return new WildcardTypeImpl(
                new Type[]{Object.class},
                bound instanceof WildcardType
                        ? ((WildcardType) bound).getLowerBounds()
                        : new Type[]{bound}
        );
    }
Returns a type that represents an unknown supertype of {@code bound}. For
example, if {@code bound} is {@code String.class}, this returns {@code ?
super String}.
core/src/main/java/com/alibaba/fastjson2/util/BeanUtils.java