public <ConfigType extends ConfigInstance> ConfigType toInstance(Class<ConfigType> clazz, String configId) {
        return ConfigInstanceUtil.getNewInstance(clazz, configId, this);
    }
@Test
    public void test_empty_payload() {
        Slime slime = new Slime();
        slime.setObject();
        IntConfig config = new ConfigPayload(slime).toInstance(IntConfig.class, "");
        assertThat(config.intVal(), is(1));
    }