How to get Last Modified Date of a Confleunce Space programmatically?

I am trying to figure out the new way of retrieving a Confluence Space programmatically in Java. Currently I have achieved this in code, which does return the correct space object:

    @Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
    public Response getUnusedSpaces(@QueryParam("date") String date, @Context UriInfo uriInfo) {"Data Received: " + uriInfo.getRequestUri().getQuery());
        try {
            Optional<Space> spaceJTS = spaceService.find(new Expansion("history.lastupdated")).withKeys("JTS").fetch();
            JSONObject obj = new JSONObject();
            obj.put("auth", true);
            obj.put("spaceKey", spaceJTS.get().getKey());
            log.error("Space details: " + spaceJTS.toString());
            String ret = obj.toString();
            return Response.status(Response.Status.OK).entity(ret).type(MediaType.TEXT_PLAIN).build();
        } catch (JSONException e) {
            return Response.status(Response.Status.NOT_FOUND).entity("Could not found space object").type(MediaType.TEXT_PLAIN).build();

However, how do I get that “history.lastupdated” value? I have tried various ways but I can’t seem to retrieve it. Any ideas?