@Test
  void mapAndDecodeExecutesMapFunction() throws Exception {
    server.enqueue(new MockResponse().setBody("response!"));

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

    assertThat("RESPONSE!").isEqualTo(api.post());
  }
The type of a parameter value may not be the desired type to encode as. Prefer the interface
type.
core/src/test/java/feign/FeignUnderAsyncTest.java