CLONE -Unable to add package after it was added and removed

Unable remove a rule package when it was added after it has been added and removed.
I have seen the issue JBRULES-358. My test go a little far than JBRULES-358.
I remove the package again when it was added for the seconn time, then an exception was thrown.

My test case is:

public void testRuleBaseRemove() throws Exception

{ RuleBase ruleBase = RuleBaseFactory.newRuleBase(); File file = new File("test.drl"); //add and remove PackageBuilder builder = new PackageBuilder(); builder.addPackageFromDrl(new FileReader(file)); Package pkg = builder.getPackage(); ruleBase.addPackage(pkg); ruleBase.removePackage(pkg.getName()); //add and remove again builder = new PackageBuilder(); builder.addPackageFromDrl(new FileReader(file)); pkg = builder.getPackage(); ruleBase.addPackage(pkg); ruleBase.removePackage(pkg.getName()); }

the exception is throw:

java.lang.NullPointerException
at org.drools.reteoo.HashedObjectSinkList.remove(HashedObjectSinkList.java:102)
at org.drools.reteoo.ObjectTypeNode.remove(ObjectTypeNode.java:245)
at org.drools.reteoo.AlphaNode.remove(AlphaNode.java:211)
at org.drools.reteoo.AlphaNode.remove(AlphaNode.java:211)
at org.drools.reteoo.LeftInputAdapterNode.remove(LeftInputAdapterNode.java:285)
at org.drools.reteoo.TerminalNode.remove(TerminalNode.java:297)
at org.drools.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:589)
at org.drools.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:244)
at org.drools.common.AbstractRuleBase.removePackage(AbstractRuleBase.java:338)
at com.zte.ums.uep.pal.fm.osf.rules.core.RuleBaseTest.testRuleBaseRemove(RuleBaseTest.java:71)
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:324)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)