getOldObject() of ObjectUpdatedEvent is returning same value as getObject()

Create a fact file public class TestFact { private String testString; public String getTestString() { return testString;} public void setTestString( String testString) { this .testString = testString;} @Override public String toString() { return testString;} } Create a test.drl file when $test : TestFact(testString == "input" ) then $test.setTestString( "output" ); update($test); Create a Listener public class TestRuntimeListener implements org.kie.api.event.rule.RuleRuntimeEventListener { @Override public void objectDeleted( final ObjectDeletedEvent event) {} @Override public void objectInserted( final ObjectInsertedEvent event) {} @Override public void objectUpdated( final ObjectUpdatedEvent event) { System .out.println( "Old and New are the same? " + event.getOldObject() == event.getObject()); System .out.println( "Old value=" + even event.getOldObject()); System .out.println( "New value=" + even event.getObject()); } } Execute org.kie.api.runtime.KieSession kSession = [Initialize KieSession] kSession.addEventListener( new TestRuntimeListener()); TestFact fact = new TestFact; fact.setString( "input" ); kSession.insert(fact); kSession.fireAllRules(); Expected Output Old and New are the same? false Old value=input New value=output Actual output Old and New are the same? true Old value=output New value=output