Streams.concat(ss.node_props, ss.edge_props)
    .map(p -> new Pair<>(p.name, p.type))
    .distinct()
    .collect(groupingBy(Pair::getValue0))
    .forEach((name, props) -> {
        // If prop. appears with only one type, set the type otherwise use Object
        // (like autoschema does for everything).
        Class type = Object.class;
        if (props.size() == 1) {
            try {
                type = Class.forName(props.get(0).getValue1());
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
                log.fatal("Class look up failed %s -> %s", name, props.get(0).getValue1())
            }
        }

        // NOTE: it fails on this line
        m.makePropertyKey(name).dataType(type).cardinality(Cardinality.SINGLE).make();
    });

m.commit();
gts.tx().commit();