public static <C> AsyncBuilder<C> builder() {
    return new AsyncBuilder<>();
  }
@Test
  void mapAndDecodeExecutesMapFunction() throws Throwable {
    server.enqueue(new MockResponse().setBody("response!"));

    TestInterfaceAsync api =
        AsyncFeign.builder().mapAndDecode(upperCaseResponseMapper(), new StringDecoder())
            .target(TestInterfaceAsync.class, "http://localhost:" + server.getPort());

    assertThat(unwrap(api.post())).isEqualTo("RESPONSE!");
  }