@Test
  void overrideQueryMapEncoder() throws Exception {
    server.enqueue(new MockResponse());

    String url = "http://localhost:" + server.getPort();
    QueryMapEncoder customMapEncoder =
        ignored -> {
          Map<String, Object> queryMap = new HashMap<>();
          queryMap.put("key1", "value1");
          queryMap.put("key2", "value2");
          return queryMap;
        };

    TestInterface api =
        Feign.builder().queryMapEncoder(customMapEncoder).target(TestInterface.class, url);
    api.queryMapEncoded("ignored");

    assertThat(server.takeRequest()).hasQueryParams(Arrays.asList("key1=value1", "key2=value2"));
    assertThat(server.getRequestCount()).isEqualTo(1);
  }
Shows exception handling isn't required to coerce 204 to null or empty
core/src/test/java/feign/FeignBuilderTest.java