@Test
  public void veryLongResponseNullLength() {
    server.enqueue(
        new MockResponse().setBody("AAAAAAAA").addHeader("Content-Length", Long.MAX_VALUE));
    TestInterface api =
        newBuilder().target(TestInterface.class, "http://localhost:" + server.getPort());

    Response response = api.post("foo");
    // Response length greater than Integer.MAX_VALUE should be null
    assertThat(response.body().length()).isNull();
  }
Some client implementation tests should override this test if the PATCH operation is
unsupported.
core/src/test/java/feign/client/AbstractClientTest.java