* publicly visible subclass), and I doubt any of our current or future Kotlin extensions for the
 * package will refer to the class. Plus, @ParametricNullness is only a temporary workaround,
 * anyway, so we just need to get by without the annotations here until Kotlin better understands
 * our other nullness annotations.
 */
final class Synchronized {
  private Synchronized() {}

And these models are all sharing a lot of the data and duplicating attribute names and types.

We could do better.

We can declare a `UserBase` model that serves as a base for our other models. And then we can make subclasses of that model that inherit its attributes (type declarations, validation, etc).

All the data conversion, validation, documentation, etc. will still work as normally.

Then we use the request directly, and extract the body as `bytes`. This means that FastAPI won't even try to parse the request payload as JSON.

And then in our code, we parse that YAML content directly, and then we are again using the same Pydantic model to validate the YAML content:

{* ../../docs_src/path_operation_advanced_configuration/tutorial007_py39.py hl[24:31] *}

/// tip

### Security vulnerabilities

Do not report security vulnerabilities to the public issue tracker. Follow our [Security Vulnerability Disclosure Policy](https://github.com/gradle/gradle/security/policy).

### Follow the Code of Conduct

    .build();
```

With a server that holds a certificate and a client that trusts it we have enough for an HTTPS
handshake. The best part of this example is that we don't need to make our test code insecure with a
a fake `HostnameVerifier` or `X509TrustManager`.

Certificate Authorities
-----------------------

The above example uses a self-signed certificate. This is convenient for testing but not

Upgrading to OkHttp 4
=====================

OkHttp 4.x upgrades our implementation language from Java to Kotlin and keeps everything else the
same. We’ve chosen Kotlin because it gives us powerful new capabilities while integrating closely
with Java.

We spent a lot of time and energy on retaining strict compatibility with OkHttp 3.x. We’re even
keeping the package name the same: `okhttp3`!

There are three kinds of compatibility we’re tracking:

         * layer of fallback before consulting the system property, we could try
         * com.sun.security.auth.module.NTSystem.
         *
         * But for now, we use the value from the system property as our best guess.
         */
        return fromSystemProperty;
      } catch (InvocationTargetException e) {
        throwIfUnchecked(e.getCause()); // in case it's an Error or something

        queue.add(task);
        return;
      }

      oldRunCount = workerRunCount;

      // If the worker is not yet running, the delegate Executor might reject our attempt to start
      // it. To preserve FIFO order and failure atomicity of rejected execution when the same
      // Runnable is executed more than once, allocate a wrapper that we know is safe to remove by

        queue.add(task);
        return;
      }

      oldRunCount = workerRunCount;

      // If the worker is not yet running, the delegate Executor might reject our attempt to start
      // it. To preserve FIFO order and failure atomicity of rejected execution when the same
      // Runnable is executed more than once, allocate a wrapper that we know is safe to remove by

     * of the child. The general idea is to adjust inherited URLs to match the project layout (in SCM).
     *
     * <p>This calculation is only a heuristic based on our conventions.
     * In detail, the algo relies on the following assumptions: <ul>
     * <li>The parent uses aggregation and refers to the child via the modules section</li>
     * <li>The module path to the child is considered to