knowledge-api: NPE when calling KnowledgeBaseAdapter.new{Stateless|Stateful}KnowledgeSession(null)

Description of problem:

The legacy knowledge-api throws a NPE at:

org.drools.impl.adapters.KnowledgeBaseAdapter.newStatelessKnowledgeSession(KnowledgeBaseAdapter.java:103)

and

org.drools.impl.adapters.KnowledgeBaseAdapter.newStatefulKnowledgeSession(KnowledgeBaseAdapter.java:90)

when you supply a null KnowledgeSessionConfiguration.

Workaround is to call newStatelessKnowledgeSession()/newStatefulKnowledgeSession() methods instead, so setting the severity to medium.

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

BRMS 6.0.1 ER2

How reproducible:

Try to run the previously mentioned methods with null argument.

Actual results:

The NPE is thrown.

Expected results:

The code runs without NPE.