entity_A.getAspects().add(aspect_A);
entity_A.setModified(true);
aspect_A.setParent(entity_A);
aspect_A.setModified(true);
aspect_A.addChild(model);
aspect_A.addChild(visualization);
aspect_A.addChild(simulation);
SerializeTreeVisitor visitor = new SerializeTreeVisitor();
runtime.apply(visitor);
String serialized = visitor.getSerializedTree();