request.addHeader("Accept", "text/plain")

    httpClient.execute(request).use { response ->
      assertThat(response.code).isEqualTo(200)
      assertThat(EntityUtils.toString(response.entity)).isEqualTo("hello, Apache HttpClient 5.x")
    }

    val recorded = server.takeRequest()
    assertThat(recorded.headers["Accept"]).isEqualTo("text/plain")