MPS-20774 You can read model only inside read actions: 1. There's little reason to send out node read events when we access meta-model. E.g. model.nodes(Kind).property, to access attributes of a specific concept, triggers read for a whole model, which seems excessive. 2. It's argued each note access shall bear at least model read lock, even to access read-only meta-model object. There's no common opinion, however. Given a lot of legacy code that keeps SNode and does SNode.getConcept().getQualifiedName(), we decided not to impose requirement to hold a read lock to access concept for now.