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**:

	// ErrDuplicatedKey occurs when there is a unique key constraint violation
	ErrDuplicatedKey = errors.New("duplicated key not allowed")
	// ErrForeignKeyViolated occurs when there is a foreign key constraint violation
	ErrForeignKeyViolated = errors.New("violates foreign key constraint")
	// ErrCheckConstraintViolated occurs when there is a check constraint violation

### 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.

    }

    /**
     * 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
     */

     * @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

# TFCI_BAZEL_TARGET_SELECTING_CONFIG_PREFIX. "Available" means there is
# an entry in tensorflow/.bazelrc for build:rbe_TFCI_BAZEL_TARGET...
#                                           ^^^^
# This env is only valid when RBE is available on the selected platform, since
# it enables a derived --config setting.  If RBE is not available (i.e. there
# is no --config setting), bazel would fail and quit. This script does a quick

# 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**.

    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);
  }

  /**

   * needed.
   *
   * A single spinlock ("busy") is used for initializing and
   * resizing the table, as well as populating slots with new Cells.
   * There is no need for a blocking lock; when the lock is not
   * available, threads try other slots (or the base).  During these
   * retries, there is increased contention and reduced locality,
   * which is still better than alternatives.
   *
   * Per-thread hash codes are initialized to random values.