@Override
        public void serialize(final Map.Entry entry, final JsonGenerator jsonGenerator, final SerializerProvider serializerProvider)
                throws IOException {
            final Map<Object,Object> m = new HashMap<>();
            if (entry != null) m.put(entry.getKey(), entry.getValue());
            jsonGenerator.writeObject(m);
        }
Coerces {@code Map.Entry} to a {@code Map} with a single entry in it.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphson/JavaUtilSerializersV3.java