OkHttp perseveres when the network is troublesome: it will silently recover from common connection
problems. If your service has multiple IP addresses, OkHttp will attempt alternate addresses if the
first connect fails. This is necessary for IPv4+IPv6 and services hosted in redundant data
centers. OkHttp supports modern TLS features (TLS 1.3, ALPN, certificate pinning). It can be
configured to fall back for broad connectivity.

    }

    @Test
    @DisplayName("close/release manage usage and transport lifecycle")
    void testReleaseLifecycle() {
        SmbSessionImpl session = newSession();

        // First release drops usage to zero and releases transport
        session.release();
        verify(transport, times(1)).release();
        assertFalse(session.isInUse());

        // Next release goes below zero and throws

    * This will be done by sending a POST request (from *your API*) to some *external API* provided by that external developer (this is the "callback").

## The normal **FastAPI** app { #the-normal-fastapi-app }

Let's first see how the normal API app would look like before adding the callback.

It will have a *path operation* that will receive an `Invoice` body, and a query parameter `callback_url` that will contain the URL for the callback.

This could be useful if for example you live in a country that restricts some URLs.

### Disable the automatic docs { #disable-the-automatic-docs }

The first step is to disable the automatic docs, as by default, those use the default CDN.

To disable them, set their URLs to `None` when creating your `FastAPI` app:

{* ../../docs_src/custom_docs_ui/tutorial001.py hl[8] *}

  /**
   * This counter prevents an ABA issue where a thread may successfully schedule the worker, the
   * worker runs and exhausts the queue, another thread enqueues a task and fails to schedule the
   * worker, and then the first thread's call to delegate.execute() returns. Without this counter,
   * it would observe the QUEUING state and set it to QUEUED, and the worker would never be
   * scheduled again for future submissions.
   */

                (byte) 0x05, (byte) 0x06, (byte) 0x07, (byte) 0x08
              },
              0x89abcdef,
              0x0123456789abcdefL, // asInt/asLong as above, due to equal eight first bytes
              "efcdab89674523010102030405060708"),
          new ExpectedHashCode(
              new byte[] {(byte) 0xdf, (byte) 0x9b, (byte) 0x57, (byte) 0x13},
              0x13579bdf,
              null,

///

### Lifespan function { #lifespan-function }

The first thing to notice, is that we are defining an async function with `yield`. This is very similar to Dependencies with `yield`.

{* ../../docs_src/events/tutorial003.py hl[14:19] *}

The first part of the function, before the `yield`, will be executed **before** the application starts.

   *
   * @param bytes the input buffer
   * @param off the offset in the buffer of the first byte to read
   * @param len the number of bytes to read from the buffer
   */
  public static boolean isWellFormed(byte[] bytes, int off, int len) {
    int end = off + len;
    checkPositionIndexes(off, end, bytes.length);
    // Look for the first non-ASCII character.
    for (int i = off; i < end; i++) {
      if (bytes[i] < 0) {

        printErrors(result);

        Iterator<Artifact> i = result.getArtifacts().iterator();
        assertEquals(n, i.next(), "n should be first");
        assertEquals(m, i.next(), "m should be second");

        // inverse order
        set = new LinkedHashSet<>();
        set.add(m);
        set.add(n);

        ingesters = newIngesters;
    }

    /**
     * Returns the array of registered ingesters sorted by priority.
     * The returned array contains all ingesters in priority order
     * (lower priority numbers first).
     *
     * @return the sorted array of ingesters
     */
    public Ingester[] getIngesters() {
        return ingesters;
    }