Java 추가 없이 Java URLConnection의 사용자 에이전트를 설정하는 방법은 무엇입니까?

$ nc -l -p 8080

GET /foobar HTTP/1.1
User-Agent: Java/1.6.0_30
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

GET /foobar HTTP/1.1
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;

public class TestUrlOpener {

    public static void main(String[] args) throws IOException {
        URL url = new URL("http://localhost:8080/foobar");
        URLConnection hc = url.openConnection();
        hc.setRequestProperty("User-Agent", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2");

        System.out.println(hc.getContentType());
    }

}