public Set<String> roles() {
        ImmutableSet.Builder<String> roles = ImmutableSet.builder();
        if (object.has(ROLES)) {
            ArrayNode roleNodes = (ArrayNode) object.path(ROLES);
            roleNodes.forEach(r -> roles.add(r.asText()));
        }
        return roles.build();
    }
@Test
    public void roles() {
        cfg.roles(ROLES);
        print(cfg);
        assertEquals("not roles", ROLES, cfg.roles());
    }