*
 * <p>{@code CharSink} provides two kinds of methods:
 *
 * <ul>
 *   <li><b>Methods that return a writer:</b> These methods should return a <i>new</i>, independent
 *       instance each time they are called. The caller is responsible for ensuring that the
 *       returned writer is closed.
 *   <li><b>Convenience methods:</b> These are implementations of common operations that are

        assertTrue(pacCredentialType.isCredentialTypeCorrect());
    }

    /**
     * Tests the isCredentialTypeCorrect method with a null byte array.
     * This test is indirect as the constructor would throw an exception.
     * We can't instantiate the class with null, so we can't directly test this method's behavior with null.
     * However, the constructor logic `!isCredentialTypeCorrect()` covers this.

 * href="https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentMap.html">before
 * {@code default} methods were introduced</a>. For newer methods, like {@code forEach}, it inherits
 * their default implementations. When those implementations invoke methods, they invoke methods on
 * the {@code ForwardingConcurrentMap}.
 *
 * @author Charles Fry
 * @since 2.0
 */
@GwtCompatible

 *
 * <p>{@code CharSource} provides two kinds of methods:
 *
 * <ul>
 *   <li><b>Methods that return a reader:</b> These methods should return a <i>new</i>, independent
 *       instance each time they are called. The caller is responsible for ensuring that the
 *       returned reader is closed.
 *   <li><b>Convenience methods:</b> These are implementations of common operations that are

 *
 * <p>{@code CharSource} provides two kinds of methods:
 *
 * <ul>
 *   <li><b>Methods that return a reader:</b> These methods should return a <i>new</i>, independent
 *       instance each time they are called. The caller is responsible for ensuring that the
 *       returned reader is closed.
 *   <li><b>Convenience methods:</b> These are implementations of common operations that are

/**
 * A map entry which forwards all its method calls to another map entry. Subclasses should override
 * one or more methods to modify the behavior of the backing map entry as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingMapEntry} forward <i>indiscriminately</i> to

{* ../../docs_src/extending_openapi/tutorial001_py39.py hl[13:14,25:26] *}

### Die Methode überschreiben { #override-the-method }

Jetzt können Sie die Methode `.openapi()` durch Ihre neue Funktion ersetzen.

{* ../../docs_src/extending_openapi/tutorial001_py39.py hl[29] *}

### Es testen { #check-it }

<img src="/img/tutorial/generate-clients/image06.png">

In this case, you have:

* `ItemsService`
* `UsersService`

### Client Method Names { #client-method-names }

Right now, the generated method names like `createItemItemsPost` don't look very clean:

```TypeScript
ItemsService.createItemItemsPost({name: "Plumbus", price: 5})
```

  protected ForwardingObject() {}

  /**
   * Returns the backing delegate instance that methods are forwarded to. Abstract subclasses
   * generally override this method with an abstract method that has a more specific return type,
   * such as {@link ForwardingSet#delegate}. Concrete subclasses override this method to supply the
   * instance being decorated.
   */
  protected abstract Object delegate();

}
```

## 🏗️ Architecture & Design Patterns

### Core Design Principles
CoreLib follows a **utility-class pattern** where most functionality is exposed through static methods:

- **Assertion-based validation** - All methods validate inputs using `AssertionUtil.assertArgumentNotNull()` and `AssertionUtil.assertArgumentNotEmpty()`