public Traversal.Admin<S, Map> getMergeTraversal() {
        return mergeTraversal;
    }
Gets the traversal that will be used to provide the {@code Map} that will be used to search for elements.
This {@code Map} also will be used as the default data set to be used to create the element if the search is not
successful.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/MergeElementStep.java