@Override
  @Test
  public void reasonPhraseIsOptional() throws IOException, InterruptedException {
    server.enqueue(new MockResponse().setStatus("HTTP/1.1 " + 200));

    final AbstractClientTest.TestInterface api =
        newBuilder()
            .target(AbstractClientTest.TestInterface.class, "http://localhost:" + server.getPort());

    final Response response = api.post("foo");

    assertThat(response.status()).isEqualTo(200);
    assertThat(response.reason()).isNull();
  }
Tests client-specific behavior, such as ensuring Content-Length is sent when specified.
java11/src/test/java/feign/http2client/test/Http2ClientTest.java