RetrofitTest.java

public class RetrofitTest {


    @Test
    public void configure() throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        mapper.registerModule(new JodaModule());

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://httpbin.org")
                .addConverterFactory(JacksonConverterFactory.create(mapper))
                .client(new OkHttpClient())
                .build();

        final TestService service = retrofit.create(TestService.class);

        final Call<Object> call = service.post(new TestMessage());

        final Response<Object> result = call.execute();
        assertThat(result, notNullValue());
    }

    public interface TestService {
        @POST("/post")
        Call<Object> post(@Body TestMessage message);

    }

    @JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.NON_PRIVATE)
    public static class TestMessage {
        DateTime now = new DateTime();
        LocalDate today = new LocalDate();
    }
}