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

    }

    /**
     * Checks if there is a previous page available.
     *
     * @return true if there is a previous page, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether there is a previous page available.
     *
     * @param existPrePage true if there is a previous page, false otherwise
     */

    }

    /**
     * Checks if there is a previous page available.
     *
     * @return true if there is a previous page, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether there is a previous page available.
     *
     * @param existPrePage true if there is a previous page, false otherwise
     */

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);
  }

  /**

There is some assistance in the IDE for this plus a lot of validation that is applied at build time and on CI, but it is useful to keep these constraints in mind as well.

See [Gradle runtimes](runtimes.md) for a list of these runtimes and more details.

### Build execution model

            // Optimization to skip streaming, distincting, and collecting to a new list when there is zero or one
            // project, aka there can't be duplicates.
            return filtered;
        }

        // Distinct the projects to avoid duplicates.  Duplicates are possible in multi-module projects.
        //
        // Given a scenario where there is an aggregate POM with modules A, B, C, D, and E and project E depends on

    /** The total number of records */
    private int allRecordCount;

    /** The total number of pages */
    private int allPageCount;

    /** Whether there is a previous page available */
    private boolean existPrePage;

    /** Whether there is a next page available */
    private boolean existNextPage;

    /** List of page numbers for navigation */
    private List<Integer> pageNumberList;