private HasContainer getIndexKey(final Class<? extends Element> indexedClass) {
        final Set<String> indexedKeys = ((AbstractTinkerGraph) this.getTraversal().getGraph().get()).getIndexedKeys(indexedClass);

        final Iterator<HasContainer> itty = IteratorUtils.filter(hasContainers.iterator(),
                c -> c.getPredicate().getBiPredicate() == Compare.eq && indexedKeys.contains(c.getKey()));
        return itty.hasNext() ? itty.next() : null;

    }
List of iterators opened by this step.
tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/process/traversal/step/sideEffect/TinkerGraphStep.java