@Override
        public GraphSONIo create() {
            if (null == graph) throw new IllegalArgumentException("The graph argument was not specified");
            return new GraphSONIo(this);
        }
Create a new builder using the specified version of GraphSON.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphson/GraphSONIo.java