}

  @Override
  public Iterator<E> iterator() {
    if (iterator == null) {
      // TODO: throw something else? Do we worry that people's code and tests
      // might be relying on this particular type of exception?
      throw new IllegalStateException();
    }
    try {
      return iterator;
    } finally {
      iterator = null;
    }
  }

Create form parameters the same way you would for `Body` or `Query`:

{* ../../docs_src/request_forms/tutorial001_an_py39.py hl[9] *}

For example, in one of the ways the OAuth2 specification can be used (called "password flow") it is required to send a `username` and `password` as form fields.

The <abbr title="specification">spec</abbr> requires the fields to be exactly named `username` and `password`, and to be sent as form fields, not JSON.

   *     unrecoverable errors, callers should prefer more specific types, avoiding {@code
   *     Throwable.class} in particular.
   * @param fallback the {@link Function} to be called if the input fails with the expected
   *     exception type. The function's argument is the input's exception. "The input's exception"
   *     means the cause of the {@link ExecutionException} thrown by {@code this.get()} or, if

          boolean haveBeenCalled;

          @Override
          public Integer computeNext() {
            if (haveBeenCalled) {
              throw new AssertionError("Should not have been called again");
            } else {
              haveBeenCalled = true;
              throw sneakyThrow(new SomeCheckedException());
            }
          }
        };

    void implementationRejectsNulls() {
        SmbFilenameFilter filter = (dir, name) -> {
            if (dir == null || name == null) {
                throw new NullPointerException("dir and name must be non-null");
            }
            return true;
        };

        NullPointerException npe1 = assertThrows(NullPointerException.class, () -> filter.accept(null, "x"));

    int listenerCount = 20;
    CountDownLatch listenerLatch = new CountDownLatch(listenerCount);

    // Test that listeners added both before and after the value is available
    // get called correctly.
    for (int i = 0; i < 20; i++) {

      // Right in the middle start up a thread to close the latch.
      if (i == 10) {
        new Thread(() -> latch.countDown()).start();
      }

     */
    public FacetInfo() {
        // Default constructor
    }

    /**
     * Initializes the facet configuration from Fess configuration properties.
     * This method is called after dependency injection to load default facet settings.
     */
    @PostConstruct
    public void init() {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

        assertNotNull(trans2QueryPathInfo);

        // Configuration is accessed during initialization
        // Verify at least that getPid() and getTransactionBufferSize() were called
    }

    }

    /**
     * Initializes the protocol helper by loading configured protocols from FessConfig
     * and scanning for available protocol handlers in the classpath.
     * This method is called automatically after bean construction.
     */
    @PostConstruct
    public void init() {
        final FessConfig fessConfig = ComponentUtil.getFessConfig();

	disksQuorum int

	// If set updates will be sent regularly to this channel.
	// Will not be closed when returned.
	updates    chan<- dataUsageEntry
	lastUpdate time.Time

	// updateCurrentPath should be called whenever a new path is scanned.
	updateCurrentPath func(string)
}

// Cache structure and compaction:
//
// A cache structure will be kept with a tree of usages.