[rules-users] Collect CE requires a non-argument Exception..

I'm getting following exception when tried to insert an object(which has a Long field and three List reference) retrieved from dao in rule conseqence. an instance of List(which is not possible). Please someone clarify this. Thanks in advance. org.drools.spi.ConsequenceException: org.drools.RuntimeDroolsException: Collect CE requires a non-argument constructor for the return type at org.drools.base.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:13) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:558) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:518) Caused by: org.drools.RuntimeDroolsException: Collect CE requires a non-argument constructor for the return type at org.drools.rule.Collect.instantiateResultObject(Collect.java:69) at org.drools.reteoo.CollectNode.assertTuple(CollectNode.java:111) at org.drools.reteoo.CompositeTupleSinkAdapter.propagateAssertTuple(CompositeTupleSinkAdapter.java:30) at org.drools.reteoo.JoinNode.assertObject(JoinNode.java:156) at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:318) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:162) at org.drools.reteoo.Rete.assertObject(Rete.java:175) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192) at org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:911) at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:67) at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:61) at Caused by: java.lang.InstantiationException: java.util.List at java.lang.Class.newInstance0(Unknown Source) at java.lang.Class.newInstance(Unknown Source) at org.drools.rule.Collect.instantiateResultObject(Collect.java:64) ... 27 more -- View this message in context: http://www.nabble.com/Collect-CE-requires-a-non-argument-Exception..-tp20... Sent from the drools - user mailing list archive at Nabble.com.