Preview of my extension to Spark Java

HelloWorld.java

package webserver.controllers;

import spark.Request;
import spark.Response;
import webserver.annotations.inputs.NotNull;
import webserver.annotations.inputs.Range;
import webserver.annotations.request.ContentType;
import webserver.annotations.request.Handler;
import webserver.annotations.request.RequestMethod;

@Handler(path = "/", method = RequestMethod.GET, contentType=ContentType.JSON)
public class HelloWorld extends RequestHandler {
	@NotNull
	public String name;

	@NotNull
	@Range(max = 50, min = 18)
	public Integer age;

	@Override
	public Object handle(Request request, Response response) {
		return "Hello world:" + name + ", " + age;
	}

}