Created attachment 989896 [details]
A reproducer for this issue

Description of problem:

Let's say in our KJAR we have two rules and one is associated with the default session, and a client application keeps pulling the latest changes from the module.

When we modify the rule not associated with the default session, we have a NPE on the client.

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
(see attachment)
1) build and install the kjar maven project(bpms.test.01337004.kjar):
   mvn clean install

2) build and run the maven test in the project bpms.test.01337004.client:
   mvn clean package (or mvn clean test)

   it should fire the "myTestRule" and show the printout "Version 3.0 Test build.Repeat-rebuild-test" in the console.

3) change the "myTestRule", for example 
   change
      "Version 3.0 Test build.Repeat-rebuild-test"
   to
      "Version 4.0 Test build.Repeat-rebuild-test"
   and rebuild kjar by running
   mvn clean install

   the client started in step 2) should pick up the change and show the printout "Version 4.0 Test build.Repeat-rebuild-test" in the console

4) change the "mytest2" and rebuild the kjar
   mvn clean install

   the NPE error should show in the console:

   Exception in thread "Timer-0" java.lang.NullPointerException
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateResourcesIncrementally(KieContainerImpl.java:269)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.update(KieContainerImpl.java:161)
	at org.drools.compiler.kie.builder.impl.KieContainerImpl.updateDependencyToVersion(KieContainerImpl.java:114)
	at org.kie.scanner.KieRepositoryScannerImpl.updateKieModule(KieRepositoryScannerImpl.java:231)
	at org.kie.scanner.KieRepositoryScannerImpl.scanNow(KieRepositoryScannerImpl.java:218)
	at org.kie.scanner.KieRepositoryScannerImpl$ScanTask.run(KieRepositoryScannerImpl.java:198)
	at java.util.TimerThread.mainLoop(Timer.java:555)
	at java.util.TimerThread.run(Timer.java:505)


After this error pops up, any change made to the two rules mentioned above will not be picked up. 


Please note that the first rule "myTestRule" is associated with the default kieSession:
   <kbase name="kbase_test" packages="org.redhat.gss.myproject">
    <ksession name="ksession1" default="true" type="stateful" />
  </kbase>

The second rule "mytest2" is associated with a non-default kieSession:
   <kbase name="kbase_test2" packages="org.redhat.gss.pkg2">
    <ksession name="ksession2"  type="stateful" />
  </kbase>

It seems that any changes made to the non-default kieSession would cause the NPE error.

Actual results:

NPE error.

Expected results:

No error and changes on client.