JsonSerializable doesn't support Enum

Consider an Enum like

`Enum Weekday {
MONDAY, TUESDAY, WEDNESDAY ...
}`

`new JSONObject(this.getMapper().writeValueAsString(value))` will throw JSONException. I know it is a generic exception when instantiate a JSONObject like new JSONObject("WEDNESDAY"), but maybe worthwhile put into consideration how to handle this situation?

Thanks,
Robbie