@Override
    public Edge readEdge(final InputStream inputStream, final Function<Attachable<Edge>, Edge> edgeAttachMethod) throws IOException {
        throw Io.Exceptions.readerFormatIsForFullGraphSerializationOnly(this.getClass());
    }
This method is not supported for this reader.

@throws UnsupportedOperationException when called.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/io/graphson/LegacyGraphSONReader.java