assertEqualCharNodes(traverser.breadthFirst('b'), "bcda");
    assertEqualCharNodes(traverser.breadthFirst('c'), "cdab");
    assertEqualCharNodes(traverser.breadthFirst('d'), "dabc");
  }

  @Test
  public void forGraph_breadthFirstIterable_cycle() {
    Traverser<Character> traverser = Traverser.forGraph(CYCLE_GRAPH);
    assertEqualCharNodes(traverser.breadthFirst(charactersOf("a")), "abcd");

      MockResponse
        .Builder()
        .body("abc")
        .build(),
    )
    val call =
      client.newCallWithListener(
        Request
          .Builder()
          .url(server.url("/"))
          .build(),
      )
    val response = call.execute()
    assertThat(response.code).isEqualTo(200)
    assertThat(response.body.string()).isEqualTo("abc")
    response.body.close()

        assertEquals("", StringUtil.substringToLast("abc", "c"));
        assertEquals("c", StringUtil.substringToLast("abc", "b"));
        assertEquals("c", StringUtil.substringToLast("abcbc", "b"));
        assertEquals("abc", StringUtil.substringToLast("abc", ""));
        assertEquals("abc", StringUtil.substringToLast("abc", null));
        assertEquals("abc", StringUtil.substringToLast("abc", "dddd"));
    }

    /**

        FullWidthToHalfWidthAlphabetNormalizer normalizer = new FullWidthToHalfWidthAlphabetNormalizer();

        String result = normalizer.normalize("ａｂｃ あいう 123", "field");

        assertEquals("abc あいう 123", result);
    }

    @Test
    public void test_fullWidthSpacePreserved() throws Exception {

    assertEquals(java.util.Optional.of("abc"), Optional.toJavaUtil(Optional.of("abc")));
  }

  public void testToJavaUtil_instance() {
    assertEquals(java.util.Optional.empty(), Optional.absent().toJavaUtil());
    assertEquals(java.util.Optional.of("abc"), Optional.of("abc").toJavaUtil());
  }

  @SuppressWarnings("NullOptional")
  public void testFromJavaUtil() {

      MockResponse
        .Builder()
        .body("abc")
        .doNotReadRequestBody()
        .build(),
    )

    val call =
      client.newCall(
        Request(
          url = server.url("/"),
          body = SlowRequestBody,
        ),
      )

    call.execute().use { response ->
      assertThat(response.body.string()).isEqualTo("abc")
    }

    postBodyRetransmittedAfterAuthorizationFail("abc")
  }

  @Test
  fun postBodyRetransmittedAfterAuthorizationFail_HTTPS() {
    enableTls()
    postBodyRetransmittedAfterAuthorizationFail("abc")
  }

  @Test
  fun postBodyRetransmittedAfterAuthorizationFail_HTTP_2() {
    enableProtocol(Protocol.HTTP_2)
    postBodyRetransmittedAfterAuthorizationFail("abc")
  }

    assertThat(response.body.string()).isEqualTo("abc")
  }

  @Test
  fun clientAuthForNeeds() {
    val client = buildClient(clientCert, clientIntermediateCa.certificate)
    val socketFactory = buildServerSslSocketFactory()
    server.useHttps(socketFactory)
    server.requireClientAuth()
    server.enqueue(
      MockResponse
        .Builder()
        .body("abc")
        .build(),
    )

    assertThat(response2.body.string()).isEqualTo("abc")
  }

  @Test
  fun concurrentRequestWithEmptyFlowControlWindow() {
    server.enqueue(
      MockResponse
        .Builder()
        .body(Buffer().write(ByteArray(Http2Connection.OKHTTP_CLIENT_WINDOW_SIZE)))
        .build(),
    )
    server.enqueue(
      MockResponse(body = "abc"),
    )

        .Builder()
        .url(server.url("/"))
        .addHeader("Original-Header", "foo")
        .method("PUT", "abc".toRequestBody("text/plain".toMediaType()))
        .build()
    client.newCall(request).execute()
    val recordedRequest = server.takeRequest()
    assertThat(recordedRequest.body?.utf8()).isEqualTo("ABC")
    assertThat(recordedRequest.headers["Original-Header"]).isEqualTo("foo")