@FeatureDescriptor(name = FEATURE_NULL_PROPERTY_VALUES)
            default boolean supportsNullPropertyValues() {
                return true;
            }
Determines if an {@link Element} allows properties with {@code null} property values. In the event that
this value is {@code false}, the underlying graph must treat {@code null} as an indication to remove
the property.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/Graph.java