JavaDialectError when attaching a new KBuilder to an existing session

Issue

• Junit console shows following exception.

java.lang.AssertionError: [JavaDialectError message='PackageStore was unable to read resourceName='com/sample.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang/Object.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang/package-info.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='com/sample/package-info.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='com/sample/Exception.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang/Exception.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang/Throwable.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='com/sample/org.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/lang/org.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/spi.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/spi/KnowledgeHelper.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/spi/package-info.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/runtime/rule/RuleContext.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/runtime/rule/package-info.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='java/io/Serializable.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='com/sample/Foo.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/runtime/KnowledgeContext.class'']
[JavaDialectError message='PackageStore was unable to read resourceName='org/drools/runtime/package-info.class'']
[JavaDialectError message='PackageStore was unable to write resourceName='com/sample/Rule_R1_fce7c9643691482996e9c1b4d46ab798.class'']

    at org.junit.Assert.fail(Assert.java:91)
    at org.junit.Assert.assertTrue(Assert.java:43)
    at org.junit.Assert.assertFalse(Assert.java:68)
    at com.sample.test.DroolsTestOne.testDynamicRulesWithTypeDeclarationsJIRA(DroolsTestOne.java:111)
    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 org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

• On the backend Console we can see an NPE while trying to add the rule:

java.lang.NullPointerException
    at org.drools.rule.builder.dialect.java.PackageStore.write(PackageStore.java:47)
    at org.drools.commons.jci.compilers.EclipseJavaCompiler$3.acceptResult(EclipseJavaCompiler.java:380)
    at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:474)
    at org.drools.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:388)
    at org.drools.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:49)
    at org.drools.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:361)
    at org.drools.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:53)
    at org.drools.compiler.PackageRegistry.compileAll(PackageRegistry.java:71)
    at org.drools.compiler.PackageBuilder.compileAll(PackageBuilder.java:1019)
    at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:974)
    at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:456)
    at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:643)
    at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:41)
    at com.sample.test.DroolsTestOne.testDynamicRulesWithTypeDeclarationsJIRA(DroolsTestOne.java:110)
    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 org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)