@Override
    public String toString() {
        return StringFactory.stepString(this, mergeTraversal, onCreateTraversal, onMatchTraversal, outVTraversal, inVTraversal);
    }
Gets the traversal that will be used to provide the {@code Map} that will be used to identify the Direction.IN
vertex during merge.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/MergeEdgeStep.java