@Override
        public Traversal<Vertex, String> get_g_V_valueMap_unfold_mapXkeyX() {
            return g.V().valueMap().<Map.Entry<String, List>>unfold().map(m -> m.get().getKey());
        }
Tests that cover lambda steps that are used in embedded cases.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/LambdaStepTest.java