Created attachment 918147 [details]
[0] reproducer

Description of problem:


If you try to retrieve FactHandle for an object which is **not** present in the KnowledgeSession this fact handle will not have null value.

There, if you call

if (handle!=null)
ksession.update(handle,object);

you will receive NPE

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


How reproducible:
always

Steps to Reproduce:
1. Just execute the reproducer with the Drools 6 libraries - i.e. knowledge-api legacy adapter

Actual results:

	FactHandle handle = ksession.getFactHandle(msg1);

handle is not null even if the msg1 object is NOT present in the session.

Expected results:
	FactHandle handle = ksession.getFactHandle(msg1);

handle should be null if the msg1 object is not present in the session

Additional info:

Root cause seems to be the missing nullcheck in the following method
https://github.com/droolsjbpm/drools/blob/master/knowledge-api-legacy5-adapter/src/main/java/org/drools/impl/adapters/WorkingMemoryEntryPointAdapter.java#L47