@FeatureDescriptor(name = FEATURE_MAP_VALUES)
            default boolean supportsMapValues() {
                return true;
            }
Supports setting of a {@code Map} value.  The assumption is that the {@code Map} can contain
arbitrary serializable values that may or may not be defined as a feature itself.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/Graph.java