@Override
        public void serializeWithType(final Map.Entry entry, final JsonGenerator jsonGenerator,
                                      final SerializerProvider serializerProvider, final TypeSerializer typeSerializer) throws IOException {
            ser(entry, jsonGenerator, serializerProvider, typeSerializer);
        }
GraphSON serializers for classes in {@code java.util.*}.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphson/JavaUtilSerializersV1.java