@Test
  void beanQueryMapEncoderWithEmptyParams() throws Exception {
    TestInterface api =
        new TestInterfaceBuilder()
            .queryMapEncoder(new BeanQueryMapEncoder())
            .target("http://localhost:" + server.getPort());

    PropertyPojo.ChildPojoClass propertyPojo = new PropertyPojo.ChildPojoClass();

    server.enqueue(new MockResponse());
    api.queryMapPropertyPojo(propertyPojo);
    assertThat(server.takeRequest()).hasQueryParams("/");
  }
when you must parse a 2xx status to determine if the operation succeeded or not.
core/src/test/java/feign/FeignTest.java