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

    String url = "http://localhost:" + server.getPort();
    RequestInterceptor requestInterceptor =
        template -> template.header("Content-Type", "text/plain");

    TestInterface api =
        Feign.builder().requestInterceptor(requestInterceptor).target(TestInterface.class, url);
    Response response = api.codecPost("request data");
    assertThat("response data").isEqualTo(Util.toString(response.body().asReader(Util.UTF_8)));

    assertThat(server.takeRequest())
        .hasHeaders(MapEntry.entry("Content-Type", Collections.singletonList("text/plain")))
        .hasBody("request data");
  }
Shows exception handling isn't required to coerce 204 to null or empty
core/src/test/java/feign/FeignBuilderTest.java