}

  private void notifyAndClearListeners() {
    afterDone();
    // TODO(lukes): consider adding the StackOverflowError protection from the server version
    // TODO(cpovirk): consider clearing this.delegate
    for (Listener listener : listeners) {
      listener.execute();
    }
    listeners = null;
  }

  protected void afterDone() {}

  @Override

    }

    public User load(final User user) {
        User u = user;
        for (final AuthenticationChain chain : chains) {
            u = chain.load(u);
        }
        return u;
    }

    public void addChain(final AuthenticationChain chain) {
        chains = ArrayUtils.addAll(chains, chain);
    }

    protected StreamOf<AuthenticationChain> chains() {
        return stream(chains);
    }

            @Override
            public QueryBuilder execute(QueryContext context, Query query, float boost, FilterChain chain) {
                calledFirst.set(true);
                assertFalse(called.get());
                QueryBuilder builder = chain.execute(context, query, boost);
                assertTrue(called.get());
                return builder;
            }
        });

  @GwtIncompatible // Charset not supported by GWT
  public static final Charset US_ASCII = Charset.forName("US-ASCII");

  /**
   * ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
   *
   * <p><b>Java 7+ users:</b> this constant should be treated as deprecated; use {@link
   * java.nio.charset.StandardCharsets#ISO_8859_1} instead.
   *
   */
  public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");

  /**

  /** Support for {@link Iterator#remove()}. */
  SUPPORTS_REMOVE,
  /**
   * Support for {@link ListIterator#add(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_ADD,
  /**
   * Support for {@link ListIterator#set(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_SET;

  /**

  /** Support for {@link Iterator#remove()}. */
  SUPPORTS_REMOVE,
  /**
   * Support for {@link ListIterator#add(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_ADD,
  /**
   * Support for {@link ListIterator#set(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_SET;

  /**

    protected static final String OPTIONS = "OPTIONS";

    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
            throws IOException, ServletException {
        final HttpServletRequest httpRequest = (HttpServletRequest) request;
        final String origin = httpRequest.getHeader("Origin");

   */
  abstract void collectOneValue(int index, @ParametricNullness InputT returnValue);

  abstract void handleAllCompleted();

  /** Adds the chain to the seen set, and returns whether all the chain was new to us. */
  private static boolean addCausalChain(Set<Throwable> seen, Throwable param) {
    // Declare a "true" local variable so that the Checker Framework will infer nullness.

    protected void write(final String text, final String contentType, final String encoding) {
        final StringBuilder buf = new StringBuilder(50);
        if (contentType == null) {
            buf.append("text/plain");
        } else {
            buf.append(contentType);
        }
        buf.append("; charset=");
        final String enc;
        if (encoding == null) {

    firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.