javaagent not working with javaws and JNLP

I have an agent JAR (jar-with-dependencies) with premain as

public static void premain(String args, Instrumentation instrumentation) {
    log.info("Starting Swing Testing Tools");
    log.info("Adding global listener using agent");
    Toolkit.getDefaultToolkit().addAWTEventListener(new GlobalEventListener(), GlobalEventListener.WINDOW_MASK);

    log.info("Starting server");
    Thread serverThread = new Thread(new InterceptorServer());
    serverThread.start();
}

This is an interceptor JAR which will listen for all the events. This class also contains a main method. Purpose of this JAR is to intercept the JNLP so that we can get all the events fired.

Now when i run this JAR using following, the agent is working fine.

D:\temp>java -jar ListenerAgent-1.0.jar
20170716,12.04.49 [INFO ] - (la.core.Agent.premain(Agent.java:16)) Starting Swing Testing Tools
20170716,12.04.49 [INFO ] - (la.core.Agent.premain(Agent.java:17)) Adding global listener using agent
20170716,12.04.49 [INFO ] - (la.core.Agent.premain(Agent.java:20)) Starting server
20170716,12.04.49 [INFO ] - (la.core.server.InterceptorServer.run(InterceptorServer.java:30)) Server started at port : 50173
C:\Users\GAGAND~1\AppData\Local\Temp\

But when i start it using the following cmd line params, the agent doesn't responds but the JNLP opens.

D:\temp>javaws -J-javaagent:"D:\temp\ListenerAgent-1.0.jar" "D:\JNLPs\Notepad.jnlp"
D:\temp>

Here is the Manifest file:

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: Gagandeep Singh
Build-Jdk: 1.8.0_111
Specification-Title: ListenerAgent
Specification-Version: 0.0.1-SNAPSHOT
Implementation-Title: ListenerAgent
Implementation-Version: 0.0.1-SNAPSHOT
Implementation-Vendor-Id: org.gagan
Main-Class: la.core.Agent
Can-Redefine-Classes: false
Can-Retransform-Classes: true
Premain-Class: la.core.Agent

Here is the link to my repository in case you need to find any other information.

Solution

Posting the solution to this in case someone is facing the same problem.

You need to modify the javaws.policy inside JRE/bin/security folder of yours:

Backup old file
Replace the existing text with

grant { permission java.security.AllPermission; };