@Test
public void testFromJson() {

  final Problem in = Problem.localProblem("title", "detail");
  final String raw = new Gson().toJson(in);
  final ContentSupport cs = new ContentSupport();
  final Problem out = cs.fromJson(raw, Problem.class);
  assertEquals("title", out.title());
  assertEquals("detail", out.detail().get());
  assertEquals(in, out);
}