That means that, clients using your API don't have to check if the value exists or not, they can **assume the field will always be there**, but just that in some cases it will have the default value of `None`.

The way to describe this in OpenAPI, is to mark that field as **required**, because it will always be there.

Because of that, the JSON Schema for a model can be different depending on if it's used for **input or output**:

### Bigger Errors - Crashes { #bigger-errors-crashes }

Nevertheless, there might be cases where we write some code that **crashes the entire application** making Uvicorn and Python crash. 💥

And still, you would probably not want the application to stay dead because there was an error in one place, you probably want it to **continue running** at least for the *path operations* that are not broken.

     * @return the server's SID
     * @throws CIFSException if there is an error retrieving the server SID
     */
    SID getServerSid(CIFSContext tc, String authorityServerName) throws CIFSException;

    /**
     * This specialized method returns a Map of users and local groups for the
     * target server where keys are SIDs representing an account and each value

This is similar to the 200 HTTP status codes (from 200 to 299). Those "200" status codes mean that somehow there was a "success" in the request.

The status codes in the 400 range mean that there was an error from the client.

Remember all those **"404 Not Found"** errors (and jokes)?

## Use `HTTPException` { #use-httpexception }

    AtomicLongMap<K> result = create();
    result.putAll(m);
    return result;
  }

  /**
   * Returns the value associated with {@code key}, or zero if there is no value associated with
   * {@code key}.
   */
  public long get(K key) {
    return map.getOrDefault(key, 0L);
  }

  /**

# OpenAPI Webhooks { #openapi-webhooks }

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

     * @param type
     *            the hexcode of the name
     * @param scope
     *            the scope of the name
     * @return resolved addresses
     * @throws java.net.UnknownHostException
     *             if there is an error resolving the name
     */
    NetbiosAddress[] getNbtAllByAddress(String host, int type, String scope) throws UnknownHostException;

    /**

    assertThrows(RejectedExecutionException.class, () -> executor.submit(() -> {}));
    assertTrue(executor.isTerminated());

    otherTask.get();
  }

  /**
   * Test for a bug where threads weren't getting signaled when shutdown was called, only when tasks
   * completed.
   */
  public void testDirectExecutorService_awaitTermination_missedSignal() {

///

### Format the code

There is a script that you can run that will format and clean all your code:

<div class="termy">

```console
$ bash scripts/format.sh
```

</div>

It will also auto-sort all your imports.

## Tests

There is a script that you can run locally to test all the code and generate coverage reports in HTML:

    assertThrows(RejectedExecutionException.class, () -> executor.submit(() -> {}));
    assertTrue(executor.isTerminated());

    otherTask.get();
  }

  /**
   * Test for a bug where threads weren't getting signaled when shutdown was called, only when tasks
   * completed.
   */
  public void testDirectExecutorService_awaitTermination_missedSignal() {