I have created a Drools project by populating with HelloWorld rule, decision table and process files.
java_home is set to jdk11. When I am trying to run DroolsTest.java , it is throwing the below error:

java.lang.NullPointerException: Cannot invoke “org.kie.api.runtime.KieSession.insert(Object)” because “kSession” is null
at com.sample.DroolsTest.main(DroolsTest.java:25)

The same HelloWorld is working fine with Drools 7.74 version. I have copied kmodule.xml, DroolsTest.java and Sample.drl. Any help would be much much appreciated. Thank you.

kmodule.xml

<?xml version="1.0" encoding="UTF-8"?>
<kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
    <kbase name="rules" packages="com.sample.rules">
        <ksession name="ksession-rules"/>
    </kbase>
    <kbase name="dtables" packages="com.sample.dtables">
        <ksession name="ksession-dtables"/>
    </kbase>
    <kbase name="process" packages="com.sample.process">
        <ksession name="ksession-process"/>
    </kbase>
</kmodule>

DroolsTest :

package com.sample;

import org.kie.api.KieServices;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;

/**
 * This is a sample class to launch a rule.
 */
public class DroolsTest {

    public static final void main(String[] args) {
        try {
            // load up the knowledge base
            KieServices ks = KieServices.Factory.get();
            System.out.println("KieServices:"+ks);
            KieContainer kContainer = ks.getKieClasspathContainer();
            System.out.println("kContainer:"+kContainer);
            KieSession kSession = kContainer.newKieSession("ksession-rules");
            System.out.println("kSession:"+kSession);
            // go !
            Message message = new Message();
            message.setMessage("Hello World");
            message.setStatus(Message.HELLO);
            kSession.insert(message);
            kSession.fireAllRules();
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }

    public static class Message {

        public static final int HELLO = 0;
        public static final int GOODBYE = 1;

        private String message;

        private int status;

        public String getMessage() {
            return this.message;
        }

        public void setMessage(String message) {
            this.message = message;
        }

        public int getStatus() {
            return this.status;
        }

        public void setStatus(int status) {
            this.status = status;
        }

    }

}


Sample.drl:

package com.sample.rules

import com.sample.DroolsTest.Message;

rule “Hello World”
when
m : Message( status == Message.HELLO, myMessage : message )
then
System.out.println( myMessage );
m.setMessage( “Goodbye cruel world” );
m.setStatus( Message.GOODBYE );
update( m );
end

rule “GoodBye”
when
Message( status == Message.GOODBYE, myMessage : message )
then
System.out.println( myMessage );
end

I tried with eclipse and code ready studio. I tried with jdk 11 and jdk 17 . no luck..