update RMIRefListener2

Author: wh1t3p1g

src/main/java/ysoserial/exploit/PayloadHTTPServer.java

@@ -21,7 +21,6 @@ public class PayloadHTTPServer implements Runnable{
     private int port;
     private String classname;
     private String command;
-    private HttpServer server;
 
     public PayloadHTTPServer(int port, String classname, String command) {
         this.port = port;
@@ -47,7 +46,7 @@ public static void main(String[] args) {
     public void run(){
         try {
             System.err.println("* Opening Payload HTTPServer on " + port);
-            server = HttpServer.create(new InetSocketAddress(port), 0);
+            HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);
             server.createContext("/"+classname+".class", new PayloadHandler(classname, command));
             server.setExecutor(null);
             server.start();