public default GraphTraversal<S, Edge> mergeE() {
        this.asAdmin().getGremlinLang().addStep(Symbols.mergeE);
        final MergeEdgeStep<S> step = new MergeEdgeStep(this.asAdmin(), false);
        return this.asAdmin().addStep(step);
    }
Spawns a {@link GraphTraversal} by doing a merge (i.e. upsert) style operation for an {@link Edge} using an
incoming {@code Map} as an argument.

@since 3.6.0
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/dsl/graph/GraphTraversal.java