private static Event.VertexAddedEvent createVertexAddedEvent(final Traversal.Admin<Object, Object> traversal,
                                                                 final Vertex addedVertex){
        final EventStrategy eventStrategy = forceGetEventStrategy(traversal);
        return new Event.VertexAddedEvent(eventStrategy.detach(addedVertex));
    }
Register a vertex property addition event with the callback registry.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/event/EventUtil.java