Play で renderJSON の出力をカスタマイズする方法

MyController.java

package controllers;

import play.Play;
import play.mvc.Controller;
import play.mvc.results.RenderJson;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class MyController extends Controller {

    private static final Gson gson;

    static {
        GsonBuilder builder = new GsonBuilder();
	if (Play.mode.isDev()) {
	    builder.setPrettyPrinting().serializeNulls();
	}
	builder.setDateFormat("yyyy-MM-dd'T'HH:mm:ss");
	gson = builder.create();
    }

    protected static void renderJSON(Object object) {
        throw new RenderJson(gson.toJson(object));
    }

}