the following won't work:

    @Funq
    public DataContext helloFn(Map<String, Object> payload) {

but this will

    @Funq
    public MapDataContext helloFn(Map<String, Object> payload) {

investigate where and why DataContext is enough, and take appropriate action to fix it otherwise.

For instance it may be enough to ensure the contextual ObjectMapper knows to marshall into a default impl (e.g. do DataContext.as(MapDataContext.class) implicitly)