JavaでJSON-lib APIを使用してJSONオブジェクトに要素を追加するにはどうすればよいですか?

public JSONObject element(String key, Object value) - put a key/value pair in the JSONObject<strong>
</strong>

import java.util.Arrays;
import net.sf.json.JSONObject;
public class JsonAddElementTest {
   public static void main(String[] args) {
      JSONObject jsonObj = new JSONObject()
         .element("name", "Raja Ramesh")
         .element("age", 30)
         .element("address", "Hyderabad")
         .element("contact numbers", Arrays.asList("9959984000", "7702144400", "7013536200"));
      System.out.println(jsonObj.toString(3)); //pretty print JSON
   }
}

{
   "name": "Raja Ramesh",
   "age": 30,
   "address": "Hyderabad",
   "contact numbers": [
      "9959984000",
      "7702144400",
      "7013536200"
   ]
}