The quick summary is that in the example shown, when the block
Tester (which does not have any Behaviors) is run in Magic Model Analyst® (Cameo Simulation Toolkit®), the Property
Tester and the property
Foo are populated with concrete instances (it uses a
BarA), even though the lower multiplicity is 0.
If the blocks
Bar are NOT abstract this does not happen (the simulation as expected does NOT wrongly populated