@Test
  void overrideTypeSpecificDecoder() throws Throwable {
    server.enqueue(new MockResponse().setBody("success!"));

    TestInterfaceAsync api =
        new TestInterfaceAsyncBuilder()
            .decoder((response, type) -> "fail")
            .target("http://localhost:" + server.getPort());

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