@Test
 public void testEntityMarshall() throws Exception {
   Entity entity =
       Entity.builder()
           .content(sampleContent1())
           .attribute(
               Attribute.builder("testId3")
                   .value(StringExp.of("aaa"))
                   .value(StringExp.of("bbbb"))
                   .value(StringExp.of("cccc"))
                   .build())
           .attribute(
               Attribute.builder("testId4")
                   .value(StringExp.of("zzzz"))
                   .value(StringExp.of("aaaa"))
                   .value(StringExp.of("cccc"))
                   .build())
           .build();
   Category a =
       Category.builder()
           .category(Categories.SUBJECT_ACCESS)
           .entity(
               Entity.builder()
                   .attribute(Attribute.builder("testId1").value(EntityExp.of(entity)).build())
                   .build())
           .build();
   JsonElement o = json.toJsonTree(a);
   Category b = json.fromJson(o, Category.class);
   assertEquals(a, b);
 }