KieContainer.newKieSession((String) null) should return the default ksession to be consistent with getKieSessionModel(null) --------------------------------------------------------------------------------------------------------------------------- Key: DROOLS-1276 URL: https://issues.jboss.org/browse/DROOLS-1276 Project: Drools Issue Type: Enhancement Components: core engine Affects Versions: 6.5.0.CR1 Reporter: Geoffrey De Smet Assignee: Mario Fusco Priority: Critical This works to get the default kieSession: {code} String ksessionName = null; // if ksessionName is null, then the default kieSession is used KieSessionModel kieSessionModel = kieContainer.getKieSessionModel(ksessionName); {code} But this doesn't work to get the default ksession: {code} String ksessionName = null; // Fails if ksessionName is null. Should return the default ksession instead. return kieContainer.newKieSession(ksessionName); {code} The above fails if ksessioName is null with this stacktrace: {code} java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011) at java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1006) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:692) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:652) at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirectorFactory.newKieSession(DroolsScoreDirectorFactory.java:129) {code} If no default ksession exists with argument null, a nice error message should be thrown.