* potential NTLM fallback (if the server does not support kerberos).
     *
     * @param subject
     *            represents the user who perform Kerberos authentication. Should at least contain a TGT for the user.
     * @param domain
     *            domain for NTLM fallback
     * @param username
     *            user for NTLM fallback
     * @param password

      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return AbstractCatchingFuture.create(input, exceptionType, fallback, executor);
  }

  public static <V extends @Nullable Object> ListenableFuture<V> catchingAsync(
      ListenableFuture<? extends V> input,
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {

        // Test fallback logic
        assertTrue(errorHandler.shouldFallbackToTcp(hardwareError), "Hardware errors should suggest TCP fallback");
        assertFalse(errorHandler.shouldFallbackToTcp(timeoutError), "Timeout errors should not immediately suggest TCP fallback");

        // Test error classification using public API

     * Execute a callable through the circuit breaker with fallback
     *
     * @param <T> return type
     * @param callable the callable to execute
     * @param fallback fallback supplier if circuit is open
     * @return the result or fallback value
     * @throws Exception if execution fails and no fallback provided
     */
    public <T> T call(Callable<T> callable, Callable<T> fallback) throws Exception {

        UserCQ cq = new UserCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                UserCQ cf = new UserCQ();
                cqLambda.callback(cf);
                list.add(new FilterFunctionBuilder(cf.getQuery(), scoreFunctionBuilder));

    boolean ran = false;
    @Nullable Callback callback = null;

    SimpleTearDown() {}

    SimpleTearDown(Callback callback) {
      this.callback = callback;
    }

    @Override
    public void tearDown() throws Exception {
      if (callback != null) {
        callback.run();
      }
      ran = true;
    }
  }

  private interface Callback {
    void run();
  }

        WebConfigCQ cq = new WebConfigCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                WebConfigCQ cf = new WebConfigCQ();
                cqLambda.callback(cf);

    client.newCall(Request.Builder().url(server.url("/a")).build()).enqueue(callback)
    callback.await(server.url("/a")).assertBody("abc")
    client.newCall(Request.Builder().url(server.url("/b")).build()).enqueue(callback)
    callback.await(server.url("/b")).assertBody("def")
    client.newCall(Request.Builder().url(server.url("/c")).build()).enqueue(callback)
    callback.await(server.url("/c")).assertBody("ghi")

        SearchLogCQ cq = new SearchLogCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                SearchLogCQ cf = new SearchLogCQ();
                cqLambda.callback(cf);

    dispatcher.maxRequests = 2
    client.newCall(newRequest("http://a/1")).enqueue(callback)
    client.newCall(newRequest("http://b/1")).enqueue(callback)
    client.newCall(newRequest("http://c/1")).enqueue(callback)
    client.newCall(newRequest("http://a/2")).enqueue(callback)
    client.newCall(newRequest("http://b/2")).enqueue(callback)

    val dispatcherQueueStartC1 = eventRecorder.removeUpToEvent<DispatcherQueueStart>()