I am using Drools 4.0.3. I have a rule that I believe should work but causes a NullPointerException at runtime.

The rule phrased this way causes a NullPointerException:
rule "Create Order Limit"
    when
        CandleSeries( $instrument : instrumentSpecification )       
    then
        insert(new OrderConstraint( $instrument ));       
end

While the same rule phased like this works fine:

rule "Create Order Limit"
    when
        $candle : CandleSeries( )       
    then
        insert(new OrderConstraint( $candle.getInstrumentSpecification() ));       
end

Is this right? I was looking at rule example 10.27 in the Drools guide and it's written exactly like rule #1 is.

Here is the full stack trace of the rule execution from version 1:

java.lang.NullPointerException
    at org.activequant.core.domainmodel.TimeSeries.getInstrumentSpecification(Unknown Source)
    at org.drools.base.org.activequant.core.domainmodel.CandleSeries2216507$getInstrumentSpecification.getValue(Unknown Source)
    at org.drools.base.ClassFieldExtractor.getValue(ClassFieldExtractor.java:127)
    at org.drools.rule.Declaration.getValue(Declaration.java:197)
    at sequitem.quanteq.ruleflow.Rule_Create_Order_Limit_0ConsequenceInvoker.evaluate(Rule_Create_Order_Limit_0ConsequenceInvoker.java:17)
    at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550)
    at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:514)
    at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:462)
    at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:424)
    at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java:50)
    at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java:24)
    at sequitem.quanteq.rules.RandomMarketEntryRulesTest.testRandomMarketEntryRules(RandomMarketEntryRulesTest.java:55)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at junit.framework.TestCase.runTest(TestCase.java:168)
    at junit.framework.TestCase.runBare(TestCase.java:134)
    at junit.framework.TestResult$1.protect(TestResult.java:110)
    at junit.framework.TestResult.runProtected(TestResult.java:128)
    at junit.framework.TestResult.run(TestResult.java:113)
    at junit.framework.TestCase.run(TestCase.java:124)
    at junit.framework.TestSuite.runTest(TestSuite.java:232)
    at junit.framework.TestSuite.run(TestSuite.java:227)
    at junit.textui.TestRunner.doRun(TestRunner.java:116)
    at junit.textui.TestRunner.doRun(TestRunner.java:109)
    at junit.textui.TestRunner.run(TestRunner.java:77)
    at junit.textui.TestRunner.run(TestRunner.java:62)
    at sequitem.quanteq.rules.RandomMarketEntryRulesTest.main(RandomMarketEntryRulesTest.java:63)
E
Time: 36.687
There was 1 error:
1) testRandomMarketEntryRules(sequitem.quanteq.rules.RandomMarketEntryRulesTest)org.drools.spi.ConsequenceException: java.lang.NullPointerException
    at org.drools.base.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:14)
    at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:553)
    at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:514)
    at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:462)
    at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:424)
    at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java:50)
    at sequitem.quanteq.rules.engine.StatefulEngine.execute(StatefulEngine.java:24)
    at sequitem.quanteq.rules.RandomMarketEntryRulesTest.testRandomMarketEntryRules(RandomMarketEntryRulesTest.java:55)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at sequitem.quanteq.rules.RandomMarketEntryRulesTest.main(RandomMarketEntryRulesTest.java:63)
Caused by: java.lang.NullPointerException
    at org.activequant.core.domainmodel.TimeSeries.getInstrumentSpecification(Unknown Source)
    at org.drools.base.org.activequant.core.domainmodel.CandleSeries2216507$getInstrumentSpecification.getValue(Unknown Source)
    at org.drools.base.ClassFieldExtractor.getValue(ClassFieldExtractor.java:127)
    at org.drools.rule.Declaration.getValue(Declaration.java:197)
    at sequitem.quanteq.ruleflow.Rule_Create_Order_Limit_0ConsequenceInvoker.evaluate(Rule_Create_Order_Limit_0ConsequenceInvoker.java:17)
    at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:550)
    ... 23 more

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