@Test
public void serializeMultipleResourceStringId() throws Exception {

    LWM2MResourceInstance inst0 = new LWM2MResourceInstance(LWM2MID.from("today"), "Instance One");
    LWM2MResourceInstance inst1 = new LWM2MResourceInstance(LWM2MID.from("yesterday"), "2");
    inst1.setType(LWM2MResourceType.INTEGER);
    LWM2MResource resource = new LWM2MResource(LWM2MID.from("0"), inst0, inst1);
    String json = serializer.serialize(resource);
    System.out.println(json);
    assertThat (json, equalTo("{\"e\":[{\"n\":\"0/today\",\"sv\":\"Instance One\"},{\"n\":\"0/yesterday\",\"v\":2}]}"));
}