@Override
        public Map<String, List<Property>> apply(final Traverser<Map<String, List<Property>>> mapTraverser) {
            final Map<String, List<Property>> values = mapTraverser.get();
            final Map<String, List<Property>> converted = new HashMap<>();

            values.entrySet().forEach(p -> {
                final List l = p.getValue().stream().map(property -> property.value()).collect(Collectors.toList());
                converted.put(p.getKey(), l);
            });

            return converted;
        }
Takes a {@link Map} of a {@link List} of {@link Property} objects and unwraps the {@link Property#value()}.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/PartitionStrategy.java