@Override
    public void apply(final Traversal.Admin<?, ?> traversal) {
        final EventStrategyCallback callback = new EventStrategyCallback(eventQueue);
        TraversalHelper.getStepsOfAssignableClass(Mutating.class, traversal).forEach(s -> s.getMutatingCallbackRegistry().addCallback(callback));
    }
Applies the appropriate detach operation to elements that will be raised in mutation events.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/EventStrategy.java