Given this rule

rule "show no gaps"
when
not Gap()
then
System.out.println( "No gaps!" );
end

the ActivationCreatedEvent references an Activation, where the list of fact handles (getFactHandles) contains one element, but its Object is null:
Fact null @0:0:27032609:1306428912:0:DEFAULT
But the list of objects (getObjects) returns a list where there is an object:
Object (org.drools.reteoo.InitialFactImpl): org.drools.reteoo.InitialFactImpl@4dde85f0

This should be changed; neither a fact handle nor an object should be returned if there are no user objects participating in the activation.