QueueingHandler(
EventQueue queue, EventFactory factory,
NodeState before, NodeState after) {
this.queue = queue;
this.factory = factory;
this.pathTracker = new PathTracker();
this.beforeIdentifierTracker = new IdentifierTracker(before);
if (after.exists()) {
this.identifierTracker = new IdentifierTracker(after);
this.parentType = getPrimaryType(after);
this.parentMixins = getMixinTypes(after);